Reflection type optical sensor and image generation apparatus

ABSTRACT

A reflection type optical sensor that detect a surface condition of a moving body and that is used for an image generation apparatus which forms images on a recording media includes a light-emitting device which has a plurality of light emitter systems including at least two light-emitting members and a light-emitting optical system having a plurality of light-emitting lenses corresponding to a plurality of the light emitter systems and guiding light emitted from the light emitter systems to the moving body and a light-receiving device which has a light receiver system including at least two light-receiving members and a light-receiving optical system having light-receiving lenses corresponding to the at least two light-receiving members and guiding light reflected by the moving body to the light receiver system. The image generation apparatus has further a surface condition judging device in addition to the reflection type optical sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on and claims priority from each ofJapanese Patent Application Number 2012-199379, filed on Sep. 11, 2012and Japanese Patent Application Number 2012-204291, filed on Sep. 18,2012, the disclosure of which is hereby incorporated by reference hereinin its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image generation apparatus regardingcopy machines, laser beam printers, facsimile terminals and plottermachines.

2. Description of the Related Art

Image generation apparatuses that make color images have been widelyused for or applied to color copy machines, printers and facsimileterminals, plotter machines etc. and moreover applied to multi-functionprinters (MFP), such as those shown in references 1-3. Such imagegeneration apparatus develops images by forming a latent image on thesurface of an image carrier holder and transfer developing agent such astoner to the latent image. Next to such development process, the imagegeneration is completed by transferring the developed images ontorecording medium such as a piece of paper and fixing the images in aprocess such that the transferred images are fixed using a fixing membersuch as fixing belt etc.

In repeating such image fixing process, abrasion and/or scratch areoften made on the surface of the fixing member. As a concrete example,carrying out to repeat the fixing process for the A4 size paper laid inthe longitudinal direction (that is to pass the paper in thelongitudinal direction along the machine) using an image generationapparatus that enables to use copy paper of both A4 and A3 sizes,longitudinal streak scratches are made at the positions, on the surfaceof the fixing belt, which are the longitudinal peripheries of A4conventional paper. Such streak scratches are made due to paper debris(such as that of binder or additive) which is divorced from the paper bycutting machine process. The paper debris is attached to bothlongitudinal peripheries of the paper and abrades the surface of thefixing belt. When a fixing process is carried out using A4 and/or A3size paper laid in transverse direction (that is to pass the paper inthe transverse direction along the machine), a grazing streak comes outto the surface of the images. The appearance of this grazing streaklooses the quality of the developed image.

The conventional technologies that may relate to the present inventionare found in Japanese Publication of Patent Applications Nos.115-113739, 2007-34068 and 2006-251165 (called reference 1, reference 2and reference 3, respectively, hereinafter), all of which areincorporated by reference.

The inventions described in the references 1 to 3 disclosecountermeasures that are to prevent such degradation of the imagequality. For example, an optical sensor, that detects the reflectedlight on the surface of a fuser roller to which light is emitted from alight source, is attached to the image generation apparatus described inthe reference 1. According to the intensity of the reflected lightdetected by the optical sensor, the reflectivity of the surface of thefuser roller is calculated. The image generation apparatus generates analarm when the reflectivity is lower than a predetermined value sincethe lowering is caused by scratches on the surface of the fuser roller,offset or degradation of a surface condition thereof. People judge thetime of exchanging of the fuser roller.

SUMMARY OF THE INVENTION

A first purpose of the present invention is to solve such a problemthat, as provided in the reference 1, it has not been possible to decidethe existence of the actual scratch or to detect the position or thewidth thereof since the condition of the surface of the fixing belt isroughly judged by merely calculating the reflectivity thereof andcomparing with a predetermined value.

Further to the above purpose, a second purpose of the present inventionis to solve the following problem. That is from the following causalrelation. An endless fixing belt that is popularly used for the fixingmember has problems such that degradation of optical performance orreliability of operation since the optical sensor cannot detect thereflected light that reflected on the fixing belt due to the deviationsin the distance from the optical source to the light-illuminatedposition thereof or the angle of the light-illuminated portion againstthe optical source due to ruffling, floppy or curling thereof likelyhappens. Due to such deviations, the optical sensor cannot exactlydetect the reflected light from the fixing belt since the light isdiffused on the surface of the belt and therefore the optical detectionsystem results into losing reliability. Due to such unreliablecapability of optical detection, there is a problem such that an alarmis generated in despite the time to exchange the fixing member has notcome yet.

According to the reference 2, an invention of image generationapparatuses such that whole of surface of the fixing members is abradedto prevent such a concentration that the scratches are generated on aparticular portion of the resultant image is provided. However, theinvention does not disclose the method to detect the generation ofscratches or the status of the scratches. According to the reference 3,an invention of image generation apparatuses such that more developer issupplied to the portion where scratches are found than the portion whereno scratches are found for the developing process and the scratches canbe obscured. As the result, frequent exchange or replacement of parts isnot necessary so that it is possible to cut the maintenance costs.However, new technology for the image generation apparatuses is recentlyrequired so that precise detection of the scratches and/or the status ofthe scratched in a quick fashion and maintaining high quality images.

In order to accomplish the first and the second purposes of the presentinvention, an image generation apparatus that includes the followinglight-emitting optical system is disclosed. That is a reflection typeoptical sensor detecting a surface condition of a moving body and beingused for an image generation apparatus which forms images on recordingmedia, comprising a light-emitting device which has a plurality of lightemitter systems including at least two light-emitting members and alight-emitting optical system having a plurality of light-emittinglenses corresponding to a plurality of the light emitter systems andguiding the light emitted from the light emitter systems to the movingbody and a light-receiving device which has a light receiver systemincluding at least two light-receiving members and a light-receivingoptical system having light-receiving lenses corresponding to the atleast two light-receiving members and guiding light reflected by themoving body to the light receiver system. In other words, the reflectiontype optical sensor that senses the condition of a moving body, used foran image generation apparatus that forms images on recording media,includes;

-   1) a light-emitting device having a plurality of light emitter    systems that include at least two light-emitting members and a    light-emitting optical system that has a plurality of lenses each    corresponding to each of the plurality of light emitter systems and    guides the light emitted from the emission systems to a moving body,    and-   2) a light-receiving device having a light receiver system that    includes at least two light-receiving members and a light-receiving    optical system that has light-receiving lenses corresponding to each    of the at least two light-receiving members and guides the reflected    light at the moving body to the light receiving system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of a color printer which isan embodiment of an image generation apparatus according to the presentinvention.

FIG. 2 is a schematic magnified side view of fixing members of the imagegeneration apparatus shown in FIG. 1.

FIG. 3 is a schematic whole view of a surface detection device accordingto the present invention.

FIG. 4 is a schematic view of a surface condition sensing device in adirection vertical to the rotational axis of the heating roller.

FIG. 5A is a schematic side view of the reflection type optical sensorregarding the first embodiment in a direction of width thereof.

FIG. 5B is a schematic front view of the reflection type optical sensorshown in FIG. 5A from light-emitting member in a moving direction.

FIG. 5C is a schematic back view of the reflection type optical sensorshown in FIG. 5A from the light-receiving members.

FIG. 5D is a schematic plan view of a board that supports thelight-emitting members and the light-receiving member included in thereflection type optical sensor shown in FIG. 5A in the separatingdirection.

FIG. 6 is a schematic view that depicts a flow chart of the operatingprinciple of a reflection type optical sensor.

FIG. 7 is a schematic that depicts a flow chart of the operatingprinciple of a surface condition judging device.

FIG. 8A is a schematic that depicts an output of the reflection typeoptical sensor, specifically, the relation of the intensity of thereflected light against the position along the principal scanningdirection.

FIG. 8B is a diagram that shows the relation of the differential of theintensity of the reflected light against the position along theprincipal scanning direction.

FIG. 8C is, similar to FIG. 8A, a diagram that shows the relation of theintensity of the reflected light against the position along theprincipal scanning direction in a view of judging scratch level.

FIG. 9A is a diagram that shows the relation of a detection result R(n)using of the reflection type optical sensor against a light-illuminatedposition of an optical spot.

FIG. 9B is a diagram that shows the relation of the differential of thedetection result R(n) using of the reflection type optical sensoragainst a light-illuminated position of an optical spot.

FIG. 9C is a diagram that shows a way to determine the position where noscratches exist.

FIG. 9D is, similar to FIG. 9A, with a consideration of gradient of themoving body.

FIG. 9E is a diagram where the ordinate of the diagram shown in FIG. 9Dis expanded.

FIG. 10A is a schematic side view of the reflection type optical sensorin the width direction thereof.

FIG. 10B is a schematic front view of the reflection type optical sensorshown in FIG. 10A from the light-emitting member in the movingdirection.

FIG. 10C is a schematic back view of the reflection type optical sensorshown in FIG. 10A from the light-emitting member in the movingdirection.

FIG. 10D is a schematic plan view of the board that supports thelight-emitting member shown and the light-receiving member included inthe reflection type optical sensor shown in FIG. 10A in the separatingdirection.

FIG. 11A is a schematic side view of the reflection type optical sensorregarding the third embodiment in the direction of width thereof.

FIG. 11B is a schematic front view of the reflection type optical sensorshown in FIG. 11A from a light-emitting member in the moving direction.

FIG. 11C is a schematic back view of the reflection type optical sensorshown in FIG. 11A from a light-receiving member in the moving direction.

FIG. 11D is a schematic plan view of the board that supports alight-emitting member and a light-receiving member included in areflection type optical sensor shown in FIG. 11A in the separatingdirection.

FIG. 11E is a diagram that shows an output variation of thelight-receiving member regarding the second embodiment when the light isemitted in a skew angle B of 0 to +/−1.0 degree with 0.25 degrees stepusing a reflection type optical sensor (LEDa(7)) regarding the secondembodiment applied to a fixing belt (a moving body) as a test object.

FIG. 11F is a diagram that shows the output variation of thelight-receiving member regarding the third embodiment when the light isemitted in a skew angle B of 0 to +/−1.0 degree with 0.25 degrees stepusing a reflection type optical sensor (LEDb(7)) regarding the thirdembodiment applied to a fixing belt (a moving body) as a test object.

FIG. 11G is a diagram that shows an output variation of thelight-receiving member used in the second embodiment when the light isemitted in a skew angle B of 0 to +/−1.0 degree with 0.25 degrees stepusing a reflection type optical sensor (LEDb(8)) regarding the secondembodiment applied to a fixing belt (a moving body) as a test object.

FIG. 11H is a diagram that shows an output variation of thelight-receiving member used in the second embodiment when the light isemitted in a skew angle B of 0 to +/−1.0 degree with 0.25 degrees stepusing a reflection type optical sensor (LEDb(8)) regarding the thirdembodiment applied to a fixing belt (a moving body) as a test object.

FIG. 12A is a schematic side view of the reflection type optical sensorregarding the fourth embodiment in the direction of the width thereof.

FIG. 12B is a schematic front view of the reflection type optical sensorshown in FIG. 12A from a light-emitting member in the moving direction.

FIG. 12C is a schematic back view of the reflection type optical sensorshown in FIG. 12A from a light-receiving member in the moving direction.

FIG. 12D is a schematic plan view of the board that supports alight-emitting member and a light-receiving member included in thereflection type optical sensor shown in FIG. 12A in the separatingdirection.

FIG. 13A is a schematic side view of the reflection type optical sensorregarding 5 in the direction of the width thereof.

FIG. 13B is a schematic front view of the reflection type optical sensorshown in FIG. 13A from a light-emitting member in the moving direction.

FIG. 13C is a schematic back view of the reflection type optical sensorshown in FIG. 13A from a light-receiving member in the moving direction

FIG. 13D is a schematic plan view of a board that supports alight-emitting member and a light-receiving member included in areflection type optical sensor shown in FIG. 13A in the separatingdirection.

FIG. 14A is a schematic side view of the reflection type optical sensorregarding the sixth embodiment.

FIG. 14B is a schematic front view of the reflection type optical sensorshown in FIG. 14A from a light-emitting member in moving direction.

FIG. 14C is a schematic back view of the reflection type optical sensorshown in FIG. 14A from a light-receiving member in the moving direction

FIG. 14D is a schematic plan view of the board that supports alight-emitting member and a light-receiving member included in areflection type optical sensor shown in FIG. 14A in the separatingdirection.

FIG. 15A is a diagram that shows distribution of detection output of aplurality of light-receiving members (those called PD_(—)1 to PD_(—)18)when light-emitting member LED(2-3) turns on, where PD and LED are theabbreviations implying of “photo diode” and “light-emitting diode”,respectively.

FIG. 15B is a diagram that shows distribution of detection output of aplurality of light-receiving members (those from PD_(—)1 to PD_(—)18)when light-emitting members LED(2-3), LED(5-3) and LED(8-3) aresimultaneously turned on.

FIG. 16A is a schematic front view of the reflection type optical sensoraligned in the width direction observed in the vertical direction rightto fixing belt.

FIG. 16B is a schematic view of the reflection type optical sensorregarding the ninth embodiment aligned with a tilt angle to widthdirection and moving direction from the direction of planar direction ofthe fixing belt.

FIG. 17A is a schematic that shows the alignment of reflection typeoptical sensor regarding the eleventh embodiment against the location ofwidth periphery of recording media (such as A4 etc. blanks) regardingthe eleventh embodiment in a view of a fixing belt.

FIG. 17B is a schematic that shows the alignment of reflection typeoptical sensor regarding the eleventh embodiment against the location ofwidth periphery of recording media (such as A5 etc. blanks) regardingthe eleventh embodiment in a view of a fixing belt.

FIG. 17C is a schematic that shows the alignment of reflection typeoptical sensor regarding the eleventh embodiment against the location ofwidth periphery of recording media (such as A6 etc. blanks) regardingthe eleventh embodiment in a view of a fixing belt.

FIG. 18 is a schematic that shows the status of the reflection typeoptical sensor (regarding the twelfth embodiment) extending to wholewidth of fixing belt in the surface direction.

FIG. 19 is a schematic of overview of the image generation apparatusregarding the fourteenth embodiment.

FIG. 20 is a schematic extended view of the fixing member shown in FIG.19.

FIG. 21 is a schematic whole assembly view of the reflection typeoptical sensor and a surface condition judging device.

FIG. 22 is a schematic to explain the status when longitudinal streakscratches are generated on a fixing belt by an edge (or periphery) of A4size paper in a longitudinal-laid direction.

FIG. 23A is a schematic cross-sectional view of the reflection typeoptical sensor regarding the fourteenth embodiment scanned in theprimarily scanning direction for the purpose of explaining a structurethereof.

FIG. 23B is a schematic cross-sectional view of the reflection typeoptical sensor regarding the fourteenth embodiment scanned in thesecondarily scanning direction for the purpose of explaining a structurethereof.

FIG. 24 is a schematic of FIG. 23A is a schematic of a cross-sectionalview of a PD and light-receiving lens included in a reflection typeoptical sensor regarding the fourteenth embodiment scanned in thesecondarily scanning direction for the purpose of explaining a structurethereof.

FIG. 25 is a schematic to explain details of as structure of a lensarray included in a reflection type optical sensor used for thefourteenth embodiment.

FIG. 26 is a schematic plan view of the board that supports an LED and aPD used for the fourteenth embodiment.

FIG. 27 is a schematic to explain a light reflection at the plannerportion.

FIG. 28A is a schematic cross-sectional view of the reflection typeoptical sensor scanned in the primarily scanning direction for thepurpose of explaining a structure thereof.

FIG. 28B is a schematic cross-sectional view of the reflection typeoptical sensor scanned in the secondarily scanning direction for thepurpose of explaining a structure thereof.

FIG. 29 is a schematic cross-sectional view of a PD and alight-receiving lens included in the reflection type optical sensorgiven as an example for comparison.

FIG. 30 is a schematic to explain a structure of a lens array includedin the reflection type optical sensor given as an example forcomparison.

FIG. 31 is a schematic of plan view of a board that supports alight-emitting diode (an LED) and a photo diode (a PD) give as anexample for comparison.

FIG. 32 is a flow chart showing operation of the reflection type opticalsensor.

FIG. 33 is a flow chart showing operation of a surface condition judgingdevice.

FIG. 34A is a diagram showing intensity of the reflected light detectedat the detection region A regarding an example of comparison.

FIG. 34B is a diagram showing differential of intensity of the reflectedlight detected at the detection region A.

FIG. 34C is a diagram showing an amount of decrease of the intensity ofthe reflected light detected.

FIG. 35A is a diagram showing an intensity of the reflected lightdetected at the detection region A given as an example for comparisonfor the purpose of explaining a process to judge positions of scratches.

FIG. 35B is a diagram showing differential of an intensity of thereflected light detected at the detection region A given as an examplefor comparison for the purpose of explaining a process to judgepositions of scratches.

FIG. 36A is a diagram specifying positions where differential values areconfined in a small range as +/−20 against locations of scratches asgiven an example for comparison.

FIG. 36B is a diagram specifying depth of scratches.

FIG. 37 is a diagram that has an extended ordinate of FIG. 36B.

FIG. 38 is a diagram that shows the results of output variation of a PDincluded in a reflection type optical sensor given in an example forcomparison and the fourteenth embodiment.

FIG. 39A is a schematic to explain a structure of the reflection typeoptical sensor regarding the fifteenth embodiment, specifically aschematic of the cross-sectional view of the reflection type opticalsensor regarding fifteenth embodiment scanned in the direction of theprimarily scanning direction.

FIG. 39B is a schematic to explain a structure of the reflection typeoptical sensor regarding the fifteenth embodiment, specifically aschematic cross-sectional view of the reflection type optical sensorregarding fifteenth embodiment scanned in the direction of thesecondarily scanning direction.

FIG. 40 is a schematic cross-sectional view of a PD and alight-receiving lens included in a reflection type optical sensorregarding fifteenth embodiment scanned in the direction of the secondarydirection.

FIG. 41 is a schematic to explain details of a structure view of a lensarray included in a reflection type optical sensor regarding thefifteenth embodiment.

FIG. 42 is a schematic plan view of the board that supports an LED and aPD used in the fifteenth embodiment.

FIG. 43 is a diagram that shows the results of output variation of a PDincluded in the reflection type optical sensor regarding the fourteenthand fifteenth embodiments.

FIG. 44A is a schematic to explain a structure of the reflection typeoptical sensor regarding the sixteenth embodiment, specifically aschematic cross-sectional view of the reflection type optical sensor inthe primarily scanning direction.

FIG. 44B is a schematic to explain a structure of the reflection typeoptical sensor regarding the sixteenth embodiment, specifically aschematic cross-sectional view of the reflection type optical sensor inthe secondarily scanning direction.

FIG. 45 is a schematic cross-sectional view of a PD and alight-receiving lens included in a reflection type optical sensorregarding the sixteenth embodiment.

FIG. 46 is a schematic plan view of the board that supports an LED and aPD regarding the sixteenth embodiment.

FIG. 47A is a schematic to explain a structure of the reflection typeoptical sensor regarding the seventeenth embodiment, specifically aschematic of the cross-sectional view of the reflection type opticalsensor in the primarily scanning direction.

FIG. 47B is a schematic to explain a structure of the reflection typeoptical sensor regarding the seventeenth embodiment, specifically aschematic of the cross-sectional view of the reflection type opticalsensor in the secondarily scanning direction.

FIG. 48 is a schematic to explain a structure view of a lens arrayincluded in a reflection type optical sensor regarding the seventeenthembodiment.

FIG. 49 is a schematic to explain details of a structure view of a lensarray included in a reflection type optical sensor regarding theseventeenth embodiment.

FIG. 50 is a schematic plan view of the board that supports an LED and aPD regarding the seventeenth embodiment.

FIG. 51A is a diagram that shows the result of output variation of a PDincluded in a reflection type optical sensor regarding the fourteenthwith respect to output distribution of a PD when one LED is powered on.

FIG. 51B is a diagram that shows the result of output variation of a PDincluded in a reflection type optical sensor with respect to outputdistribution of a PD when three LEDs are simultaneously powered on.

FIG. 52A is a schematic to explain a light-illuminated position of anoptical spot when a reflection type optical sensor is aligned inparallel to the primary scanning direction.

FIG. 52B is a schematic to explain a light-illuminated position of anoptical spot when a reflection type optical sensor is aligned in 45 deg.angle against the primary scanning direction.

FIG. 53A is a schematic to show a layout plan of the reflection typeoptical sensor which is placed near the edge (or periphery) of smallsize paper, especially for use of A4 size paper.

FIG. 53B is a schematic to show a layout plan of the reflection typeoptical sensor which is placed near the edge of small size paper,especially for use of A5 size paper.

FIG. 53C is a schematic to show a layout plan of the reflection typeoptical sensor which is placed near the edge of small size paper,especially for use of A6 size paper.

FIG. 54 is a schematic to show a view of an arrangement of thereflection type optical sensor, formed largely in the primary scanningdirection, placed on the fixing belt.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Detailed embodiments to realize the first purpose of the presentinvention is explained hereinafter in details with reference to theaccompanying drawings.

FIG. 1 is a schematic cross-sectional view of a color printer as anembodiment of an image generation apparatus. The image generationapparatus is not limited to color printers but also include copymachines, facsimile terminals, printing machines and complex machinesthat combine these functions.

In FIG. 1, the image generation apparatus includes an image formingmember 2 and a paper feed/eject member3.

In this apparatus, the image formation member 2 is built in a structurethat each visible image formed on a photo receptor drum 4 issuperimposed and transferred to an intermediate image transfer member 6on an image transfer device 5 in a first transferring process andbatch-transferred to a recording medium S (such as recording paper,recording materials, recording members etc.) in a secondary transferringprocess.

The above photo receptor drums 4 are image carrier holders that enableto form images each corresponding to a dispersed color such as a yellowcolor (Y), a cyan color (C), a magenta color (M) or a black color (K)and that have a tandem structure with four units conformal to suchcolors. For a convenience to depict a schematic, a part indicationnumber is only given to the photo receptor drum 4 of a yellow color (Y),but those of a cyan color (C), magenta color (M) and a black color (B)are the same as.

The above intermediate image transfer member 6 is an endless belt(referred to as “an image transferring belt”, hereinafter) that isopposing to the photo receptor drum 4 and is moveable in the conveyingdirection 7 shown with an arrow.

The image forming member 2 explained above has several devices in orderto image forming processes in accordance to each photo receptor drum 4corresponding to each color. In order to explain the processes of imageforming, the photo receptor drum (K) 4 of the black color, for example,an electrostatic-charging device 8, a developing device 9, a primarytransferring roller 10 (referring to a primary transferring roller of ayellow color (Y)) and a cleaning device 11 are placed in such an order.For the purpose of image forming onto the photo receptor drum 4 afterelectrostatic-charging thereto by using an electrostatic-charging device8, an optical scanning device 12 (that is a light exposing device) isused as explained later.

Superimpose image transferring to an image transferring belt 6 asexplained above is carried out from the upper stream to the downstreamin the convey direction 7 with shifting a timing of each imagetransferring so that each visible image formed on each photo receptordrum 4 of each color as yellow, cyan, magenta and black, is transferredto the same position on the image transferring belt 6 in the process ofthe image transferring belt moves to the conveying direction. Thesuperimpose image transferring is carried out by applying a voltage toeach of primary image transferring rollers 10 which are arranged tooppose to each photo receptor drum 4 across the image transferring belt6.

Each photo receptor drum 4 explained above is placed from the upperstream to the downstream in the conveying direction 7 as the order ofthe above explanation. Each of photo receptor drums 4 conform each imagestation that forms images for each of the colors as yellow, cyan,magenta and black, as well.

The image forming member 2 of the image generation apparatus 1 asexplained above further has the four image stations explained above, asecondary image transferring roller 14, a cleaning device 15, an imagetransferring belt unit 13 opposing upwardly to the each photo receptordrum 4 that constructs each of the imaging station and the opticalscanning device 12 as described above which is an optical image formingdevice opposing downwardly to these four image stations.

The image transferring belt unit 13 includes the image transferring belt6 explained above and the primary image transferring roller 10. Theimage transferring belt unit 13 includes a driving roller 16 to whichthe image transferring belt 6 is coupled and rotated therewith, otherthan the image transferring belt 6 and the primary image transferringroller 10.

Among these image transferring rollers, a driven roller 17 includes atension assist device 18 that adds tensile force to the imagetransferring belt 6 such as a spring that biases to push the drivenroller 17 in a direction away from the driving roller 16.

The secondary image transferring roller 14 is an image transferringmember that is rotating driven to the image transferring belt 6 and isplaced opposing to the image transferring belt 6.

The cleaning device 15 as explained above is to clean the imagetransferring belt 6 and placed opposing to the image transferring belt6.

The above image transfer device 5 comprises the image transferring beltunit 13, the primary image transferring roller 10, the secondary imagetransferring roller 14 and the cleaning device 15.

The above optical scanning device 12 includes semiconductor laserdiodes, coupling lenses, f-theta lenses, toroidal lenses, mirrors androtational polygon mirrors to form electrostatic latent images on thephoto receptor drums 4 in such a manner that image forming lights 19each corresponding to each of colors is emitted to each correspondingphoto receptor drums 4.

The cleaning device 15, not depicted in FIG. 1 for the simplicity,installed to above image transfer device 5 includes a cleaning brush anda cleaning blade which are set to oppose the image transferring belt 6and contact thereto, cleaning the image transferring belt 6 by scanningand removing foreign materials such as residual tonner etc. on thesurface of the image transferring belt 6. The cleaning device 15 alsoincludes an eject device, not depicted in FIG. 1 for a simplicity, tocarry the residual tonner removed from the image transferring belt 6 outthereof for exhausting.

The above paper feed/eject member included in the image generationapparatus 1 has a sheet container 21 that stores recording media S(whose position is only shown in the figure) such as blanks verticallypiled therein, a pair of resist rollers 23 that bring up the recordingmedium conveyed along a blank conveying pathway 22 from the sheetcontainer 21 toward an image station locating between a photo receptordrum 4 and an image transferring belt 6 at the timing to meet that oftonner image forming by means of above image station and a sensor (notshown in FIG. 1) that detects the arrival of the front edge (or frontperiphery) of the recording medium S at the pair of the resist roller23.

The sheet container 21 explained above is embodied by a paper feedingcassette that is set under the main body of the image generationapparatus 1. The feeding cassette has a convey roller 25 working as afeeding roller that contacts the upper surface of the top of therecording media S piled therein. The convey roller 25 conveys the topsheet of the recording media S to the above pair of resist roller 23 bybeing driven to rotate in counter clockwise in FIG. 1.

Moreover, the paper feed/eject member 3 has a fixing device 26 workingas a fixing unit to fix tonner on the recording media S to which atonner image is transferred, a paper ejecting roller 27 that dischargesthe recording media S, already being processed for fixing the tonner,out of the main body 24 of the image generation apparatus 1 and a paperejecting tray 28 that is formed outside of the main body 24 and pilesthe recording media S discharged out from the main body 24 by the paperejecting roller 27.

A belt-fixing device is used for the fixing device 26 explained above.

Tonner bottles 29, each for a yellow color, a cyan color, a magentacolor and black color, are installed in a space of the lower part of thepaper ejecting tray 28.

The image generation apparatus 1 depicted in FIG. 1 batch-transfers theimages, which are formed by each photo receptor drum 4 into asuperimposed color image by transferring each by each, to the recordingmedia S by using a secondary image transferring roller 14. As anothersystem, it is possible to directly superimpose all color images onto therecording media S each corresponding to each photo receptor drum 4.

FIG. 2 is a schematic of a magnified side view of the construction ofthe fixing device 26 explained above.

The fixing device 26 has a fuser roller 31, a pressing roller 32 thatapplies a pressure against the fuser roller 31, a heating roller 33which has a thermal source H therein and a fixing member (or called afixer) such as a fixing belt 35 working as a moving body and beingengaged to both the heating roller 33 and the fuser roller 31 whichrotate therewith.

In addition, the fixing device 26 has a tension roller 36 which furtherprovides tension to the fixing belt 35, a separation click 37 set at thedownstream of the conveying direction of the recording media S and atemperature sensor (not shown in FIG. 2) that senses the temperature ofthe fixing belt 35 locating above the heating roller 33.

The fuser roller 31 explained above is a composite member such thatsilicone rubber covers a metal rod thereon.

The pressing roller 32 consists of a metal rod made of aluminum, ironetc. covered with an elastic layer such as silicon rubber cover thereonand a peel ply such as a layer or PFA (a trade mark of perfluoroalkoxy)or PTFE (a trademark of polytetrafluoroethylene) formed further thereon.

The heating roller 33 mentioned above is made from a hollow pipe ofaluminum or iron and a thermal source such as halogen heater isinstalled therein.

The fixing belt 35 is a base material made of nickel or polyimide with apeel ply such as a surface layer of PFA or PTFE formed further thereonor that has further an intermediate elastic layer of silicon rubberbetween the base material and the surface layer. The fixing belt 35 isengaged to both the fuser roller 31 and the heating roller 33 whichrotate therewith and keeps appropriate tension by externally pushingwith the tension roller 36.

The separation click 37 explained above contacts to the surface of thefuser roller 31 of the fixing belt 35 at the front edge (atop) and aplurality thereof is arranged in the width direction (vertical to thepage of paper) of the fixing belt 35.

The temperature sensor explained above does not contact to the fixingbelt 35 but a non-contacting temperature sensor (that is a thermopile)is only set thereto. Instead of such temperature sensor, it is possibleto use a contacting temperature sensor (that is a thermistor).

The tension roller 36 explained above is a metal rod covered withsilicon rubber.

The fixing device 26 that is composed with these materials and membersfixe images on the recording media S by applying a pre-determinedpressure and heat at a nipping part when the recording media S come fromportions shown in bellow in the schematic of FIG. 2 toward the nippingportion being formed with the fuser roller 31 (or the fixing belt 35 andthe pressing roller 32) and enabling to hold and convey.

A surface condition detection device 41 is attached to the fixingdevices 36 as shown in FIG. 3. Such surface condition detection device41 is to detect the surface condition of the moving body (that is afixing member).

The surface condition detection device 41 comprises a reflection typeoptical sensor 42 and a surface condition judging device 43.

The reflection type optical sensor 42 as mentioned above is placed in anarrangement to oppose to the fixing belt 35 at the portion of theheating roller 33 in the fixing belt 35 (a moving body) and beconstructed to be such an detection system that receives the reflectedlight 47 each coming from a plurality of optical spots 46 each on thedifferent position in the direction of the width on the fixing belt 35by emitting the light beam 45 (or detection light) thereto.

The surface condition judging device 43 is placed in the imagegeneration apparatus 1 and connected to the reflection type opticalsensor 42 so that the surface condition judging device 43 can judge thesurface condition of the fixing bet 35 by carrying out various signalprocessing with the detected signal 48 sent from the reflection typeoptical sensors 42. The surface condition judging device 43 also has afunction to work as a controller 44 to control the reflection typeoptical sensor 42 by sending a control signal 49 thereto.

FIG. 4 is a schematic view of the surface condition detection deviceshown in FIG. 3 in the direction vertical to the rotational axis of theheating roller 33 (that is, downwardly from the upper space of FIG. 3).

In this arrangement, only one reflection type optical sensor 42 is, forexample, when an A4 blanks is used in the longitudinal-laid direction,placed for the width direction x of the fixing belt 35 that is anperiphery position 35 s which is the side of recording media S in thepassing direction or nearby thereof.

The reflection type optical sensor 42, as discussed later in details,forms a rather long detection region A on the surface of the fixing belt35 by emitting a plurality of optical spot 46 sequentially generated inthe direct position along the width direction x. Forming such ratherlong detection region A, the relative positional relation between thereflection type optical sensor 42 and the width periphery portion 35 sof the recording media S can be acceptable even for the case that therelative positional relation is not precise.

The surface condition judging device 43 can detects a surface conditionof the fixing belt 35 in a range of rather long detection region A inthe direction of the width direction x thereof by inputting thedetection signal 48 from the reflection type optical sensor 42.

The periphery of the recording media S being included in the detectionregion A, the existence, position, level etc. of scratches 51 which havea shape of longitudinal streak scratches can be quantified.

The level of the scratches 51 literally implies the degree of scratchessuch that the depth (or surface roughness) and the width (or size) etc.thereof.

Before explaining concrete embodiments of the presentation inventions,featuring the structures, the functions and the effects of theseembodiments are explained in the following paragraphs.

The following embodiments relate to the reflection type optical sensor42 that detects a surface condition of a moving body (which is a fixingbelt as discussed later) used for the image generation apparatus 1forming images on recording media.

As shown in FIGS. 10A to 10D, the reflection type optical sensor 42comprise a plurality of light emitter systems having at least twolight-emitting members 52, a plurality of light-emitting lenses 58corresponding to a plurality of the light emitter systems, alight-emitting optical system that guides the light beam 45 emitted fromthe light emitter systems to the moving body and a light-receivingoptical system 56 (referring to FIG. 5A) that, having light-receivinglenses 61 corresponding to the light-receiving members 55, guides thereflected light 47 reflected by the moving body to the light receiversystem.

The part indication numbers for the light-emitting optical system 53 andthe light receiving optical system 56 are presented in the embodimentsshown in FIGS. 5A to 5D. For the purpose of the simplicity, thesenumbers are omitted for such systems in the other figures, however theyare still these part indication numbers are consistently same for thesystems.

Since it is possible to further specifically detect, in real-time and indetails, the surface condition of the moving body in the position of thewidth direction thereof by comparing the reflected light 47 that is thelight beam 45 each received the at least two light-receiving member 55,it becomes possible to precisely detect the surface condition. Forexample, it is possible to detect precise condition such as the existingof actual scratches 51 on the moving body and the position, depth andwidth thereof.

When a plurality of light-emitting members 52 is set in thelight-emitting optical system 53, it is possible to improve theprecision in detecting the surface condition of the moving body as wellas optimize the design of the light-emitting portion 54 and thedetecting portion 57 since the light-emitting optical system 53 that haslarge diameter lenses are used for the plurality of light-emittingmember 52 can increase the intensity of the reflected light 47 from theoptical spot 46 with maintaining the pitch (or the arrangement pitch) ofa plurality of the optical spots 46 in comparison to the case when aplurality of light-emitting optical systems 53 that have small diameterlenses are used.

It is preferably to arrange each light-receiving members 55 explainedabove in such a way that, regarding the array direction of arrangement(that is the width direction x of the moving body), the optical axisposition of a plurality of the light-emitting lenses 58 eachcorresponding to the light emitter systems as explained above is set atthe position between arbitral two light-receiving members 55 among eachlight-receiving member 55 above explained or near to such twolight-receiving members 55.

The output variation of the light-receiving member 55 caused by thefluctuation of the rotation angle (that is a skew angle) around theconveying direction of the moving body (as of the recording medium 5)each light-receiving member 55 can be suppressed and stabilized by theoptical axis position of a plurality of the light-emitting lens 58 eachcorresponding to the light emitter systems as explained above being setat the position between arbitral two light-receiving members 55 amongthe each light-receiving member 55 above explained or near to such twolight-receiving members 55 regarding the array direction of arrangement(that is the width direction X of the moving body). Since thelight-receiving member 55 becomes to have a similar behavior against theskew angle in such setting, it is possible to decrease the detectionerror in accordance to the suppression or stabilization of the outputvariation.

As shown in FIGS. 12A to 12D, cylindrical lenses 62 that convert thelight (the reflected lights 47) in a single axial direction can be usedfor the light-receiving lenses 61.

By using the cylindrical lenses 61 that convert the light (the reflectedlights 47) in a single axial direction, it is possible to suppress thevariation of the receiving light distribution obtained by detectingportion 57 (against the width direction x of the moving body) incomparison to the use of spherical lenses for the light-receiving lenses61.

By using the cylindrical lenses 62 for the light-receiving lenses 61, itis possible to more precisely detect the surface condition of the movingbody since variation of the parameters (for example, the curvatureradius, the set position, the thickness of the lens) of each lens (thatis the small lens) can be removed.

As shown in FIGS. 13A to 13D, the light-emitting lenses 58 that composesthe light-emitting optical system 53 and the light-receiving lenses 61that compose the light-receiving optical system 56 are preferably formedin a integrated manor to form a lens array 63.

By forming the light-emitting lens 58 and the light-receiving lenses 61into a single element, the precision of the physical arrangement of eachlens against each other can be improved as well as improvement of theworkability to assemble each lens (such as each the light-emittinglenses 58 and the light-receiving lenses 61), that is, for example, toassemble a plurality of lenses each by each.

As shown in FIGS. 14A to 14D, it is preferred to place a light-blockingmember 65 between the light-emitter system explained above and thelight-emitting optical system 53.

As setting the light-blocking member 65 between the light emitter systemexplained above and the light-emitting optical system 53, it is possibleto more precisely detect the surface condition of the moving conditionby reducing the detection or preventing to detection of the reflectedlight 47 from the portion other than the optical spot 46 the reflectedlight 47 reflected at the lens surface of other light-emitting lens 58that does not correspond to the light-emitting member 52 that emits thelight at the light-receiving members 52.

It is preferred to expose a plurality of optical spots 46 in series tothe light.

By generating a plurality of the optical spots 46 in series by lightemission, only one spot 46 is generated at a time and the reflectedlight 47 coming from a plurality of spots is not simultaneously at thesame light-receiving position so that the precision of the detection ofthe reflected light 47 from each optical spot 47 can be improved.

It is further preferred to simultaneously generate a plurality of theoptical spots 46 by the light emission (referring to FIGS. 15A and 15B).

By simultaneously generating a plurality of the optical spots 46 to thelight, it is possible to detect the surface condition of the moving bodyquicker and more precise fashion since the scanning cycle of the opticalspot 46 in the width direction x of the moving body can be shortened incomparison to exposing a plurality of the optical spots 46 in series tothe light.

As shown in FIG. 16B, it is preferred to generating a plurality of theoptical spots 46 with arbitral angle against the array direction ofarrangement (that is the width direction of the moving body) of aplurality of the light emitter systems.

By generating a plurality of the optical spots 46 with arbitral angleagainst the array direction of arrangement (that is the width directionx of the moving body) of a plurality of the light emitter systems, evenfor the case that a plurality of the light-emitting members 52 are, forexample, placed with a certain interval distance, the separationdistance in the width direction x of a plurality of the optical spots 46can be smaller than the above certain interval distance and the positionresolution can be easily improved.

As the reflection type optical sensor 42, it is preferred to use thereflection type optical sensor 42 in the image generation apparatus 1.

Even in such use of the reflection type optical sensor 42, the imagegeneration apparatus 1 has the same functional effects.

For the image generation apparatus 1 explained above, it is preferred topartially place the reflection type optical sensor 42 at or nearby theedge of the recording medium S that the moving body conveys as shown inFIGS. 17A to 17C or over total width of the recording medium S as shownin FIG. 18.

By partially placing the reflection type optical sensor 42 at or nearbythe width periphery position 35 s of the recording medium S that themoving body conveys, it is possible to make the reflection type opticalsensor 42 into a small dimension as well as to effectively place thereflection type optical sensor 42 at or nearby the place where themoving body mostly suffers from scratches 51.

In such arrangement of the reflection type optical sensor 42, thesetting place of the reflection type optical sensor 42 can be at ornearby the position of at least one of the width periphery position 35 sof one of the recording medium S among those which have equal to orsmaller than the largest size of the recording media S conveyable by themoving body. In the view of practice, it is preferable that the placingposition of the refection type optical sensor 42 at or nearby at leastone of the width periphery positions 35 s of at least of one of thesmaller size recording media S but excluding the largest size of therecording medium S conveyable by the moving body.

By arranging the reflection type optical sensor 42 over the whole widthof the moving body, it is possible to simultaneously detect in one timea plurality of kinds of the scratches 51 that are created at thedifferent places of the recording media S, being conveyed by the movingbody, due to the size thereof so that no miss-detection happens.

The moving body used in the image generation apparatus 1 can be a fixingbelt 35 (referring to FIGS. 2 to 4).

The moving body being the fixing belt 35, it is possible to surelydetect the surface condition of the fixing belt 35 since a material(such as PFA pulverized fuel ash) is used and the fixing belt can easilyget scratches 51.

Fuser rollers 31 can be used instead of the fixing belt 35 for themoving body.

Concrete embodiments regarding the present invention are described inrelation to the above discussion.

The First Embodiment

FIGS. 5A to 5D show the most fundamental structure of the reflectiontype optical sensors 42.

The definition of the direction is generally that the width direction xof the moving body (or the fixing body such as the fixing belt 35) isthe principal direction (or the principal scanning direction), themoving direction y (or the tangential direction thereof) of the emittingportion of the optical spots 46 on the moving body (or the fixingmember) the secondary scanning direction (or the secondary scanningdirection) and separation direction between the moving body (or thefixing member) and the reflection type optical sensor 42 emittingdirection of the light beam 45 or the reflection direction of thereflected light 47.

FIG. 5A is a schematic side view of the reflection type optical sensor42 in a width direction x.

FIG. 5B is a schematic front view of the reflection type optical sensor42 shown in FIG. 5A seen from the light-emitting member 52 in the abovemoving direction y.

FIG. 5C is a schematic back view of the reflection type optical sensor42 shown in FIG. 5A seen from the light-receiving members 55 in thedirection of the moving direction.

FIG. 5D is a schematic plan view of the board 71 that supports thelight-emitting members 52 and the light-receiving member 55 in theseparating direction z above explained.

First of all, the reflection type optical sensors 42 comprise thelight-emitting members 52 (optical sources such as, for example, LEDs),the light-emitting optical system 52 that has the light-emitting lenses58 arranged to form the optical spots 46 on the surface of the fixingbelt 35 to which the light 45 is emitted and guided from thelight-emitting members 52, the light receiver system having a pluralityof light-receiving members 55 (such as light-receiving elements, forexample, PDs (photo diodes)) and one light-receiving lens 61corresponding at least two light-receiving members and further have thelight receiver system to guide the reflected light 47.

The light-emitting member 52 and the light-receiving member 55 aresupported by (or mounted on) the same board 71. The light-emittinglenses 58 and the light-receiving lenses 61 are formed into a singleelement as a lens array 63. The board 71 and the lens array 63 aresupported by the sensor body (or case) of the reflection type opticalsensor 42. The light-blocking member 65 is set in the sensor body 64 tosuppress a flare.

It is possible to form the light-blocking member 65 and the sensor body64 into an integrated plastic form.

As shown in FIG. 5B, a plurality of the light-emitting members 52 isarranged in the width direction x thereof and constructs a lightemitting system. The width direction x is the direction of arrangementof the light-emitting member 52 in the light emitter system.

The plurality of light-emitting lenses 58 is arranged in the widthdirection to construct a light emitter system. Such width direction x isthe array direction of arrangement of the light-emitting members 52 inthe light emitter system.

The constant pitch or each light-emitting member 52 arrangement in thewidth direction x is assumed to be P as well as the pitch of thearrangement each light-emitting lens 58 in the width direction x.

The light-blocking members 65 separate the spaces in the separationdirection z between the corresponding light-emitting member 52 and thelight-emitting lens 58 and block the light in the light-emitting member52 from the light in the light-emitting lens 52 so that a plurality ofthe light-blocking members 65 are arranged with a separation interval inthese adjacent spaces.

Similar light-blocking members 65 are placed in the space between thelight-emitting portion 54 and the detection portion 57.

In such structure, the light-blocking members 65 can be light-blockingsurrounding walls formed in the sensor body 64 which has a formworkshape or can be a remaining wall of the sensor body 64 which is aformwork made from a drilled block that has an opening in the end of thespace made by the formwork thereof.

The light 45 emitted from each of the light-emitting members 52 goes tothe fixing belt 35 through a corresponding light-emitting lens 58 andfrom an optical spot 46 on the surface of the fixing belt 35. Thereflection type optical sensor 42 generates a plurality of the opticalspots 46 that have an arrangement pitch P in the width direction x.

One or a plurality of the light-receiving members 55 are placed in thewidth direction x as shown in FIG. 5D. The plurality of light-receivingmembers 55 are arranged in one-to-one correspondence against eachlight-emitting members 52 as shown in FIG. 5D wherein thelight-receiving members 55 have a constant arrangement pitch P in thewidth direction. In other words, the light-emitting members 52 and thelight-receiving members 55 are both arranged with the same pitch P inthe width direction.

The light-receiving lenses 61 have no optical effects to the widthdirection x.

When the optical spots 46 are generated on the surface of the fixingbelt 35 by emitting light thereto, the reflected light 47 comes from thesurface of the fixing belt 35. Since the surface of the fixing belt 35is not mirror surface, a scattering light component 47 b is generated inaddition to the nominal reflecting light component 47 a.

A part of the reflected light 47 is guided to the light-receiving lenses61, converted only in the moving direction y of the fixing belt 35 anddetected by the light-receiving members 55. The detection of thereflected light 47 by the light-receiving members 55 is carried out oncefor each of a plurality of the optical spots 46 each having differentposition in the width direction.

The operation of the reflection type optical sensors 42 is explainedusing FIG. 6 that shows a flow chart thereof.

From the left end of FIG. 5D, the light-emitting members 52 are calledLED(1), LED(2), . . . , LED(N) and the light-receiving members 55similarly PD(1), PD(2), . . . , PD(N)

A plurality of the light-emitting members 52 repeats light-on andlight-off each from the left end thereof, in other words, carrying outsequential on/off of the light.

When a control starts, an initial value ‘1’ is set for the variable n instep 1 (or S1) and turns on the light of n-th light-emitting members 52(or LED(n)).

Then, the reflected light 47 at the fixing belt 35 is detected by aplurality of the light-receiving members 55 locating peripheral to orincluding n-th light-receiving member 55 (or PD(n)) that corresponds toLED(n) that is turned on the light.

For the simplicity of the discussion, the quantity of thelight-receiving members 55 that receive the same reflected light 47 fromidentically same optical spot 46 is odd pieces (2m+1), where m is aninteger. Therefore, PD(n−m) to PD(n+m) can simultaneously detect theidentically same reflected light 47.

When the (2m+1) pieces light-receiving members 55 detect the identicallysame reflected light 47, LED(n) is turned off.

Then in step S (or S5), the reflected light 47 detected by the (2m+1)pieces light-receiving members 55 is photo-electrically converted andamplified to be a detected signal 48. The detected signal 48 is sent tothe surface condition judging device 43 as shown in FIG. 3.

In step 6 (or S6), n+1 is substituted into n in step 7 (or S7) if n<N inthe comparison of n with N and then going back to step 1 (or S1), theabove steps are repeated until the most right-end of light-emittingmembers 52, that is LED(N), turns on/off.

When the most right-ending LED(N) turns on/off after n=N, the steprepetition is regarded as one cycle and the above sequential turn-on/offof the light ends.

However, adding step 8 (or S8) after step 6 (or S6), the abovesequential turn-on/off of the light is carried out over a plurality ofcycles and a process for averaging of the results of detection can beadded to improve the precision of the detection.

For the light-emitting members 52 that turns on/off the light, all Npieces of the light-emitting members 52 from the left-end to theright-end are not necessary to be used but arbitrary N″ (which is lessand equal to N) pieces can be used. It is not necessary to startturning-n/off of the light with the most left-ending LED(1) and to endwith the most right-ending LED(N), as well. It may work well to startturning-n/off of the light with the m-th light-emitting member 52, thatis LED(N−m), from the most left-end position and to end with (N−m)-thlight-emitting member 52, that is LED(N−m), from the most right-end.

The operation of the surface condition judging device 43 is discussed asfollows using a flow chart shown in FIG. 7.

As for the surface condition judging device 43, receiving the detectedsignal 48 sent from the (2m+1) pieces of the light-receiving members 55in step 11 (or S11), the detection result R(n) corresponding to eachLED(n) is calculated after taking summation of the detected signals 48detected at (2m+1) pieces of the light-receiving members 55. Theintensity of the reflected light corresponding to each position in thewidth direction x at the optical spots 46 in other words, on the surfaceof the fixing belt 35 is obtained by this detection result R(n).

The operation to judge the surface condition of the fixing belt 35 isdiscussed in the following.

In case that there is a scratch 51 on the surface of the fixing belt 35,the nominal reflecting light component 47 a and the scattering lightcomponent 47 b in the reflected light 47 coming from the surface of thefixing belt 35 decreases and increases, respectively in comparison tothe case that there is no scratch 51 on the surface of the fixing belt35.

As for the reflection type optical sensors 42 shown in FIGS. 5A to 5D,the intensity of the light received by the light-receiving member 55,such as PD(n), decreases in accordance with the decrease of the nominalreflecting light component 47 a when the nominal reflecting lightcomponent 47 a decreases and the intensity of the light received bylight-receiving members 55 from PD(n−m) to PD(n+m) increases inaccordance with the increase of the scattering light component 47 b whenthe scattering light component 47 b decrease. When there are scratches51, the intensity of light detected by light-receiving members 55 fromPD(n−m) to PD(n+m) decreases in total.

By measuring the intensity of the received light, the surface condition,in other words, the position and the level of scratches 51 arecalculated in a real-time fashion.

The method to judge the existence of the scratches 51 is explained inthe flowing.

Since the detection result (n), corresponding to each position in thewidth direction on the fixing belt 35, that indicates the intensity ofthe reflected light is obtained, it is possible to judge the existenceof the scratches 51 at the position where the intensity of the reflectedlight becomes low by comparing intensity of the reflected light each foreach position in the width direction x by the surface condition judgingdevice 43.

FIG. 8A is a schematic that depicts the perspective of intensity of thereflected light received by the reflection type optical sensor 42 ineach position in the width direction x (the primary scanning direction).As shown in FIG. 8B, it is possible to judge the positions of thescratches 51 (step 15 (or S15) in FIG. 7) as well as judging theexistence of the scratches 51 (step 14 (or S14) in FIG. 7) bydetermining the position of zero-crossing where the differential valuelargely changes from the negative value to the positive one.

Since it is suggested that the decrease of the intensity of thereflected light is little when the absolute value of the differential issmaller than a predetermined threshold value, it may be possible tojudge that there are no scratches 51. When it is judged that there areno scratches 51, the judgment process ends up.

In FIG. 9A, an example of the detection result R(n), using thereflection type optical sensor 42 that is specifically provided withN=24, n=3 to 22, m=2 and an arrangement pitch P=1 mm for the fixing belt35 experienced with 400,000 pieces of recording media S passing, isshown. Since the light emitted to the surface of the fixing belt 35 withthe optical spots 46 in 1 mm pitch for the reflection type opticalsensor 42, the abscissa axis indicates the light-illuminated positions(mm) of the optical spots as well as the order number n of the LED.

The differential of R(n) with regard to the width direction x, that is,more concretely the gradient of two points as R(n) and R(n+1) is shownin FIG. 9B. For the purpose of smoothening, a moving average is takenover the points R(n−1), R(n) and R(n+1) where are adjacent each otherand the gradient of such moving averaged values may be used.

In FIG. 9B, n=12.5 at the zero-cross position, which is the intermediatebetween the positions of the optical spots 46 corresponding to LED(12)and LED(13), and then it is possible to judge that a scratch 51 existsat the position of 12.5 mm.

The method to judge the level of the scratches 51 is explained in theflowing.

At step 16 (or S16) shown in FIG. 7, judgment whether to judge thedepths of the scratches 51 is done. When such judgment of the depths ofthe scratches 51 is not carried out, then the step for judgment ends upas is.

Since it is expected that the deeper (rougher) the scratches 51 are, themore the intensity of the reflected light decreases, it is possible todetect the depths of the scratches 51 by measuring the decrease of theintensity of the reflected light. In other words, the deeper (rougher)the scratches 51 are, the more the light scattered on the surface of thefixing belt 35 so that the light received by light-receiving member 55decreases, therefore it is possible to detect the depths of thescratches 51 by measuring the decrease of the intensity of the reflectedlight. FIG. 8C is a schematic that depicts the perspective of such depthdetection.

FIG. 8C shows a case that the depths of the scratches 51 are simplyobtained by measuring the minimum value for the detection results R(n),however it is expected that the light components due to the mountingstatus of the reflection type optical sensors 42 in the image generationapparatus 1 and tilt of fixing belt 35 etc. is biased to the detectionresult R(n).

In order to remove such light component for eliminating such bias, thefollowing method is taken.

Firstly, two positions, ones where scratches 51 exist and the other oneswhere no scratches 51 do, are determined.

As for the positions where scratches 51 exist, it is possible to judgein the methods as explained above.

As for the positions where no scratches 51 exist, it is possible todetermine such position that no scratches 51 exist by the result of thedifferential of the detection results R(n) with respect to the widthdirection x since the positions are those where changes of the detectionresult R(n) regarding the width direction are small so that thedifferential thereof are close to zero.

Assuming the position where scratch 51 exist be n0 and at least twopositions where no scratches 51 exist be n1 and n2, it is possible todetermine the decrease of the intensity of the reflected light by usingthe detection result R(n0) where a scratch 51 exist and those R(n1) andR(n2) where no scratches exist.

In order to remove such light component for eliminating such bias, thedistance between the detection result at the position where thescratches 51 exist and an approximated straight line that goes through aplurality of detection results at the positions where scratches 51 donot exist is used.

The determination of the decrease of the intensity of the reflectedlight is actually explained against the results of FIG. 9B.

FIG. 9C shows a small range of +/−20 regarding the differential of thedetection result at the position n0 where scratches 51 exist as shown inFIG. 9B. From FIG. 9C, it is possible to select n1=5 and n2=15 for thepositions n1 and n2 where no scratches 51 exist.

The depths of the scratches 51 (roughness of surface) are calculatedusing each detection result R(n) for n0=12.5 corresponding existence ofscratches 51 and n1=6 and n2=15 corresponding no existence of scratches51.

An approximated straight line is obtained by connecting R(n1) and R(n2)with a dotted straight line as shown in FIG. 9D. Then the depths of thescratches 51 are obtained (step 18 (or S18) shown in FIG. 7) asindicating with an arrow sign. For this example, the depth of thescratch 51 is 63.1 mm. (it is necessary to review as to whether a unit,mm of 63.1 is correct). The rate of the decrease of the intensity of thereflected light is 0.16 (16%).

As seen in FIG. 9D, there is a light component that biases the detectionresult corresponding to the depths of the scratches 51.

The larger the scratch level becomes, the more the decrease of theintensity of the reflected light.

The method for judging the widths (sizes) of the scratches 51 isexplained in the following.

At the step 19 (or S19) shown in FIG. 7, judgment whether to judge thewidths (sizes) of the scratches 51 is done. When such judgment of thewidths of the scratches 51 is not carried out, then the step forjudgment ends up as is.

The judgment of the center position of the scratches 51 where scratches51 exist is possible to be carried out as explained above.

As for the widths of the scratches 51, it is determined to calculate thepositions where the intensity of the reflected light regarding thedetection result R(n) at such position that the scratches 51 exit isless than a pre-determined value of the decrease of the intensity of thereflected light that corresponds to the depths of the scratches 51, forexample 50% thereof. Of cause the pre-determined value of the decreaseof such intensity is not confined in 50% but can be arbitrarilyselected.

FIG. 9E is a schematic that expands the axis of ordinate in verticaldirection of FIG. 9D for ease of understanding. According to FIG. 9E, itis possible to judge the full width at half maximum of the scratches 51is 3 mm.

In the assessment, all of the parameters regarding the surfaceconditions can be judged or only those necessary for the assessment maybe judged.

The Second Embodiment

FIGS. 10A to 10D are schematics to show the reflection type opticalsensors 42 (especially the reflection type optical sensors 42 a).

FIG. 10A is a schematic side view of a reflection type optical sensor 42in the width direction x thereof.

FIG. 10B is a schematic front view of the reflection type optical sensor42 shown in FIG. 10A from the light-emitting member 52 in the movingdirection y.

FIG. 10C is a schematic of back view of the reflection type opticalsensor 42 shown in FIG. 10A from the light-emitting member 52 in themoving direction y.

FIG. 10D is a schematic plan view of the board 71 that supports thelight-emitting member 52 and the light-receiving member 55 in theseparating direction z.

First of all, as shown in FIG. 10A, the reflection type optical sensors42 (or, specifically the reflection type optical sensor 42 a in thisparticular explanation) comprise a light-emitting member 52 (or,specifically a light-emitting member 52 a in this particularexplanation), a light-emitting lens 58 (or, specifically alight-emitting lens 58 a in this particular explanation) that guides andconverts the light emitted from the light-emitting member 52 to anoptical spot 46 on the surface of the fixing belt 35 and alight-receiving member 55 (or, specifically a light-receiving member 55a in this particular explanation) that receives the reflected light 47being guided by the light-receiving lens 61.

The light-emitting member 52 and the light-receiving member 55 are bothsupported (mounted) on the board 71. The board 71, the light-emittinglens 58 and the light-receiving lens 61 are supported by the sensor body64.

As shown in FIG. 10B, a plurality of the light-emitting members 52 isclosely arranged each other (for this particular case, four of thelight-emitting members 52) in the width direction x so that a pluralityof the light emitter systems is constructed and arrange.

A light-emitting lens 58 (or, specifically a light-emitting lens 58 a inthis particular explanation) corresponding to each light emitter systemcomprising a plurality (four pieces) of the light-emitting members 52 isprepared as a light-emitting optical system (multiple to one). The lensdiameter of the light-emitting lens 58 (those adopted in FIG. 10B) inthe width direction x is about four times larger as the lens diameter ofthe light-emitting lens 58 (those adopted in, for example, FIG. 5B). Thelens parameters other than the lens diameter are same as those of thelight-emitting lens 58 which is shown in FIG. 5A. The fourlight-emitting lenses 58 have an array pitch Pa (<P) in the widthdirection x.

As for the light-emitting lens 58, an anamorphic lens that has differentoptical power ratio for the width direction x and the moving direction yis adopted.

At the time to detect the surface condition of the fixing belt 35 usingthe reflection type optical sensor 42, the distance from detectedsurface or angle therefrom has variations due to surface waving,ruffling and curling of the fixing belt 35. It is difficult to removeall of these variations so that the precise detection of the surfacecondition is not possible since no correct output of the detected signal48 is obtained in detecting the surface condition of the fixing belt 35once variations of the above distance or angle between the reflectiontype optical sensors 42 and the fixing belt 35 are made.

For the present particular image generation apparatus 1, the influenceof the variation of angles due to the surface waving of the fixing belt35 is remarkably large among the deviation of distance of the detectionsurface or the angles in the reflection type optical sensors 42.

In this embodiment, an anamorphic lens that has different optical powerratio for the width direction x and the moving direction y is used. Itis possible to keep the diameter of the light beam in the movingdirection y of the reflected light 47 that is incidental to thelight-receiving lens 61 by using the anamorphic lens to optimize thecurvature radii in the moving direction y as well as keeping thediameter of the light beam in the width direction of the light thatgenerates the optical spot 46 on the surface of the fixing belt 25 witha pre-determined designed diameter. It is possible to decrease thefluctuation of the detection output by suppressing the influence of thevariation of angles due to the surface waving and avoid the degradationof the precision of the sensor detection.

A pair of a light emitter system composing with a plurality of thelight-emitting members 52 and a light-emitting lens 58 correspondingthereto composes a light emitter unit 75. The light-emitting portion 54(that comprises each light emitter system and light-emitting lens 58with multiplying of quantity of light emitter units) of the reflectiontype optical sensor 42 is constructed by arranging a plurality of thelight emitter units 75 in the width direction x.

The arrangement pitch of the light emitter units 75 in the widthdirection is P′a. In the present embodiment, the quantity of thelight-emitting members 52 a is four, however any quantity is acceptableif it is more than two.

For the purpose of easy understanding, the quantity of light emitterunits 75 is selected to be nine. However, such quantity is not confinedto be nine but those less than nine or more than nine are acceptable.

The reflection type optical sensors 42 have a plurality of optical spot46 made on the fixing belt 35 with an arrangement pitch P″a in the widthdirection x since the light beam 45 emitted from each of thelight-emitting members 52 generates an optical spot 46 on the surface ofthe fixing belt 35 through a corresponding light-emitting lens 58 in aright emitter unit 75.

As shown in FIG. 10C, a plurality of the light-receiving members 55 isarranged in the width direction x.

As shown in FIG. 10D, the line where a plurality of the light-receivingmembers 55 is arranged in the width direction is in the substantiallysame position with the optical axis 59 of the light-emitting lens 58 a.For such arrangement, the arrangement pitch of the light-receivingmembers 55 in the width direction x is P″a.

For the present embodiment of the reflection type optical sensor 42, arelation such that P′″a, P′″a, P′a/4 and P are all substantially equalis satisfied.

One light-receiving lens 61 corresponds to all light-receiving members55 that are arranged to be placed. For such light-receiving lens 61, ananamorphic lens that has different optical power ratio for the widthdirection x and the moving direction y can be adopted.

A plurality of the optical spots 46 is generated on the surface of thefixing belt 35 and the reflected light 47 is reflected from each of theoptical spots 46. Since the surface of the fixing belt 35 is not amirror surface, a scattering light component 47 b is generated inaddition to the nominal reflecting light component 47 a in thereflection and a part of the reflected light 47 is guided by thelight-receiving lenses 61 and received by the light-receiving member 55a.

The light-emitting members 52 are arranged in the width direction x witha pitch P′a in the light emitter unit 75 as shown in FIG. 10D. Theelements of the light-emitting members 52 which are composed with fourelements thereof are arranged with the width direction x with a pitchPa.

The light-receiving members 55 are arranged in the width direction witha pitch P′″a. The separation distance between the light-emitting members52 and the light-receiving members in the moving direction is P′″a.

The light-emitting members 52 and the light-receiving members 55 areeach named light-emitting members LEDa(1), LEDa(2), LEDa(N) andlight-receiving members PDa(1) PDa(2), . . . , PDa(N), respectively.

Bing possible to use the light-emitting lens 58 which has a largediameter in the width direction x due to the construction such that thereflection type optical sensors 42 a of the present embodiment has onelight-emitting lens 58 corresponding to a plurality (four pieces forthis case) of the light-emitting member 52, the pitch P″a of a pluralityof the optical spots 46 on the surface of the fixing belt 35 can be keptequal to the pitch P shown in FIG. 5 and the intensity of the incidentallight to the fixing belt 35 can be four times larger than that whereinthe reflection type optical sensors 42 as shown in FIG. 5 is used.

As is clearly understood by FIG. 10B, at least two light beams 45emitted from a plurality of the light-emitting members 52 in anidentically same light emitter unit 75 are designed to substantiallyhave surface symmetry to the surface that includes the light axis 59 ofthe light-emitting lens 58. In other words, each light emitter unit 75is designed such that correspondence between the light-emitting members52 and the optical spots 46 made on the surface of the fixing belt 35provides a reverse relation in right and left. Therefore, the lightemitter unit 75 in FIG. 10B has the most left light-emitting member 52that corresponds to the fourth optical spot 46 from the left and thefourth light-emitting member 52 from the left corresponds to the mostleft optical spot 46. The four light-emitting members 52 in the lightemitter unit 75 are symmetrically arranged in the both side from thesurface that includes the light axis 59 of the light-emitting lens 58.

In this particular embodiment, the lenses may adopt the followingparameters but are not limited to use them. The light-emitting lens 58has a curvature radius of 4.6 mm, a conical constant of 0 and a lensdiameter of 2.4 mm both in the width direction x, a curvature radius of4.3 mm, a conical constant of −2.0 and a lens diameter of 10.5 mm in themoving direction y and the lens thickness of 6.6 mm.

The light-receiving lens 61 has a curvature radius of 5.0 mm, a conicalconstant of −1.0 and a lens diameter of 17 mm both in the widthdirection x, a curvature radius of 4.8 mm, a conical constant of −1.6and a lens diameter of 10.1 mm in the moving direction y and the lensthickness of 6.6 mm.

The distance between the light-emitting lens 58 and the light-receivinglens 61 in the moving direction y is 2.53 mm and the distance of thelight-emitting member 52 to the light-emitting lens 58 in the directionof the optical axis (separation direction z) is 10.37 mm and equal tothe distance of the light-receiving member 55 to the light-receivinglens 61 in the optical axis direction.

The Third Embodiment

FIGS. 11A to 11D show the reflection type optical sensor 42 (thereflection type optical sensor 42 b) regarding the present embodiment.

FIG. 11A is a schematic side view of the reflection type optical sensor42 from the width direction x.

FIG. 11B is a schematic front view of the reflection type optical sensor42 shown in FIG. 11A from the light-emitting member 52 in the movingdirection y.

FIG. 11C is a schematic back view of the reflection type optical sensor42 shown in FIG. 11A from the light-receiving member 55 b in the movingdirection y.

FIG. 11D is a schematic plan view of a board 71 that supports thelight-emitting member 52 and a light-receiving member 55 in theseparating direction z.

In the embodiment shown in FIGS. 10A to 10D, a plurality of thelight-receiving members 55 a is arranged with a pitch P″a in the widthdirection x against the light-emitting members 52 a. As shown in FIG.10C, the plurality of light-receiving members 55 a are arranged in thesubstantially same positions of the optical axis 59 of thelight-emitting lens 58 a.

The feature of the present embodiment is that the position of theoptical axis 59 of the light-emitting lens 58 b in the width direction xis positioned in or near the intermediate position between two adjacentlight-receiving members 55 b.

First of all, as shown in FIG. 11A, the reflection type optical sensors42 (or the reflection type optical sensor 42 b) includes thelight-emitting members 52 (or the light-emitting members 52 b), thelight-emitting lens 58 (or the light-emitting lens 58 b) arranged suchthat the light beam 45 emitted from the light-emitting member 52 isguided to illuminate the moving body (or the fixing belt 35) and formsan optical spot 46 on the surface of the fixing belt 35, thelight-receiving lenses 61 (or the light-receiving lens 61 b) that isarranged to guide the reflected light 47 reflected by the fixing belt 35and a light-receiving member 55 (or the light-receiving member 55 b)that detects the reflected light 47.

The light-emitting members 52 and the light-receiving member 55 aresupported by (that is, mounted on) the identically same board 71. Theboard 71, the light-emitting lens 58 and the light-receiving lens 61 aresupported by a sensor body 64.

The modification from above embodiment is, as described above, only theposition of the light-receiving members 55. The pitch P″a of theadjacent light-receiving members 55 is not modified so that lensparameters are same as those of the above embodiment.

FIGS. 11E to 11H show the reflection type optical sensors 42 a and theoutput variation of the light-receiving member 55 when the fixing belt35 (the moving body) to be tested is tilted by every 0.25 degrees in therange of 0 degree to +/−1.0 deg., where the skew angle B is a tilt angleof the fixing belt 35 with a rotational axis in the moving direction y.

The light-emitting member 52 that turns on the light is the seventhlight-emitting member 52 (that is light-emitting members LEDa(7) andLEDb(7) as shown in FIGS. 11E and 11F, respectively) from the left sideand the eighth light-emitting member 52 (that is light-emitting membersLEDa(8) and LEDb(8) as shown in FIGS. 11G and 11H). The output of thelight-receiving member 55 is set to be unity (we call this as a relativelight-receiving output) for the skew angle B=0 degree. As mentionedabove, total summation of the detected signals 48 at the plurality oflight-receiving members 55 is the detection output (or the intensity ofthe reflected light) as the result of the detection. For the purpose ofsimplicity, the quantity of the light-receiving members 55 is limited upto 10 pieces or 8 ones.

Letting PV value be the absolute differential value between the maximumand the minimum of the detection output for the skew angle ranging of+/−1.0 deg., the PV values for the cases when different light-emittingmembers 55 turn on the light are compared for each reflection typeoptical sensors 42 a and 42 b. Idealistically, PV values should beconsistently same even for the different light-emitting members 52 turnson the light. The better, the smaller the differences are. It ispossible to judge that the smaller the PV values are, the smaller thedetection errors due to the difference of the light-emitting members 52are.

According to the results as shown in FIGS. 11E to 11H, the PV values aresmaller when the reflection type optical sensors 42 b in the presentembodiment are used than when the reflection type optical sensors 42 ain the above embodiment are used.

As discussed above, once the reflection type optical sensors 42 b aredesigned such that the fluctuation of the detection output due to a skewangle which is a tilt angle of the fixing belt 35 around the axisdirecting to the moving direction y has the same behavior even fordifferent light-emitting members 52 that turn on the light, it ispossible to suppress the detection error due to the difference of thelight-emitting members 52.

The Fourth Embodiment

FIGS. 12A to 12D depict the reflection type optical sensors 42(specifically, the reflection type optical sensors 42 c) used for thepresent embodiment.

FIG. 12A is a schematic side view of a reflection type optical sensor 42in the width direction x.

FIG. 12B is a schematic front view of the reflection type optical sensor42 as shown in FIG. 12A from a light-emitting member in the movingdirection y.

FIG. 12C is a schematic back view of the reflection type optical sensor42 as shown in FIG. 12A from the light-receiving member 55 in the movingdirection y.

FIG. 12D is a schematic plan view of the board 71 that supports thelight-emitting member 52 and the light-receiving member 55 in theseparating direction z.

An anamorphic lens is used for the light-receiving lenses 61 b of thereflection type optical sensors 42 b for the embodiment shown in FIGS.11A to 11D. However the present embodiment has a feature that acylindrical lens 62 that convert the light (reflected light 47) in oneaxis is used for the light-receiving lens 61 c of the reflection typeoptical sensors 42 c (of cause it is possible to use cylindrical lenses62 for the other embodiments). It is known that cylindrical lenses haveno optical effects to the width direction x or array direction ofarrangement of the optical spots 46 (including the case such that thearranged line of the optical spots 46 are tilted against the arraydirection of arrangement).

As shown in FIG. 12A, the reflection type optical sensors 42(particularly the reflection type optical sensor 42 c) includes thelight-emitting members 52 (particularly the light-emitting members 52c), the light-emitting lens 58 (particularly the light-emitting lens 58c) arranged such that the light beam 45 emitted from the light-emittingmember 52 is guided to illuminate the moving body (or the fixing belt35) and forms an optical spot 46 on the surface of the fixing belt 35,the light-receiving lenses 61 (particularly the light-receiving lens 61c) that is arranged to guide the reflected light 47 reflected by thefixing belt 35 and a light-receiving member 55 (particularly thelight-receiving member 55 c) that detects the reflected light 47.

The light-emitting members 52 and the light-receiving member 55 aresupported by (mounted on) identically same board 71. The board 71, thelight-emitting lens 58 and the light-receiving lens 61 are supported bya sensor body 64.

As shown in FIG. 12B, the reflection type optical sensors 42 isconstructed such that a plurality of the light-receiving members 55(particularly PDc) are arranged in the width direction x. Therefore, itis necessary to the reflected light 47 incidental to the light-receivingmembers 55 has to be converted in the moving direction y, consideringthe positions and the size of the light-receiving members 55, howevernot to in the width direction x by effecting of the light-receivinglenses 61 therein. As the result, cylindrical lenses 62 that have nooptical effects in the width direction x used for the light-receivinglenses 61.

Using cylindrical lenses 62 that has no optical effects in the widthdirection x used for the light-receiving lenses 61, it is possible tosuppress the variation of the intensity distribution of the receivinglight in the width direction x regarding the light-receiving members 55against the difference of the light emitting members 52 that turn on thelight and therefore to precisely detect the surface condition of thefixing belt 35.

In this particular embodiment, the lenses may adopt the followingparameters but are not limited to use them. The light-emitting lens 58has similar parameters to those used in each previous embodiment. Aslight-receiving lenses 61, the curvature radius and conical constant inthe width direction are different from those adopted in the firstembodiment. The curvature radius and the conical constant of thelight-receiving lenses 61 in the width direction are infinity and zero,respectively.

The position and pitch of the arrangement regarding the light-emittingmembers 52 and the light-receiving members 55 are same as those adoptedin the second embodiment.

The Fifth Embodiment

FIG. 13A to 13D depict the reflection type optical sensors 42(specifically, the reflection type optical sensors 42 d) used for thepresent embodiment.

FIG. 13A is a schematic side view of the reflection type optical sensor42 in the width direction x.

FIG. 13B is a schematic front view of the reflection type optical sensor42 as shown in FIG. 13A from a light-emitting member in the movingdirection y.

FIG. 13C is a schematic back view of the reflection type optical sensor42 as shown in FIG. 13A from the light-receiving member 55 in the movingdirection y.

FIG. 13D is a schematic plan view of the board 71 that supports thelight-emitting member 52 and the light-receiving member 55 in theseparating direction z.

In each of the previous embodiments, the reflection type optical sensors42 are designed such that the light-emitting lenses 58 and thelight-receiving lenses 61 are arranged in pre-determined positions. Thepresent embodiment features that the light-emitting lenses 58 and thelight-receiving lenses 61 are formed into a single element called a lensarray 63 (of cause it is possible to use the lens array 63 for the otherembodiments).

As shown in FIG. 13A, the reflection type optical sensors 42 (thereflection type optical sensor 42 d) includes the light-emitting members52 (the light-emitting members 52 d), the light-emitting lens 58 (thelight-emitting lens 58 d) arranged such that the light beam 45 emittedfrom the light-emitting member 52 is guided to illuminate the movingbody (or the fixing belt 35) and forms an optical spot 46 on the surfaceof the fixing belt 35, the light-receiving lenses 61 (particularly thelight-receiving lens 61 d) that is arranged to guide the reflected light47 reflected by the fixing belt 35 and a light-receiving member 55(particularly the light-receiving member 55 d) that detects thereflected light 47.

The light-emitting members 52 and the light-receiving member 55 aresupported by (mounted on) identically same board 71. The board 71, thelight-emitting lens 58 and the lens array 61 mentioned above aresupported by a sensor body 64.

For this embodiment, it can be expected to decrease the fluctuation ofthe detection output and to accurately detect the surface condition ofthe fixing belt 35 since the workability to assemble lenses (such as thelight-emitting lens 58 or the light-receiving lens 61) with therefection type optical sensors 42 and the accuracy to physically arrangea plurality of lenses can be improved.

FIGS. 14A to 14D show the reflection type optical sensors 42 of thepresent embodiment.

FIG. 14A is a schematic side view of the reflection type optical sensor42 in the width direction x.

FIG. 14B is a schematic front view of the reflection type optical sensor42 shown in FIG. 14A from the light-emitting member 52 in movingdirection y.

FIG. 14C is a schematic back view of the reflection type optical sensor42 shown in FIG. 14A from the light-receiving member 55 in the movingdirection y.

FIG. 14D is a schematic plan view of the board 71 that supports thelight-emitting member 52 and the light-receiving member 55 in theseparating direction z.

The present embodiment has the feature that the light-blocking member 65is formed in the reflection type optical sensors 42 shown in eachprevious embodiments (of cause it is possible to use the light-blockingmember 65 for the other embodiments).

As shown in FIG. 14A, the reflection type optical sensors 42(particularly the reflection type optical sensor 42 e) includes thelight-emitting members 52 (particularly the light-emitting members 52 e)that emits near infrared light, the light-emitting lens 58 particularly(the light-emitting lens 58 e) arranged such that the light beam 45emitted from the light-emitting member 52 is guided to illuminate themoving body (or the fixing belt 35) and forms an optical spot 46 on thesurface of the fixing belt 35, the light-receiving lenses 61(particularly the light-receiving lens 61 e) that is arranged to guidethe reflected light 47 reflected by the fixing belt 35 and alight-receiving member 55 (particularly the light-receiving member 55 e)that detects the reflected light 47.

The light-emitting members 52 and the light-receiving member 55 aresupported by (mounted on) identically same board 71. The board 71, thelight-emitting lens 58 and the lens array 61 mentioned above aresupported by a sensor body 64.

In the present embodiment, the light-blocking member 65 is set thereflection type optical sensors 42 to cut flare.

The flare is the light other than the reflected light 47 coming from theoptical spots 46. The light other that the reflected lights 47 comingfrom the optical spots 46 means, for example, those of the reflectedlight 47 other than the optical spots 46 on the surface of the bodingbody, the reflected light 47 on the lens surface of the light-emittinglens 58 that is the light-emitting lens 58 corresponding to thelight-emitting members 52 or on the surface of other light-emitting lens58 that does not corresponds to the light-emitting member 52 which emitsthe light, etc.

The light-blocking member 65 is designed in such a way that itinterrupts the adjacent light emitter units 75.

More concretely, the light-emitting members 52 are each set to interruptbetween the space between the light-emitting member 52 and thelight-emitting lens 58 and the external space thereof and also thebordering of these spaces.

The light-blocking member 65 is set between the light-emitting portion54 and the detecting portion 57 as well.

In such structure, the light-blocking members 65 can be light-blockingsurrounding walls formed in the sensor body 64 which has a formworkshape or can be a remaining wall of the sensor body 64 which is a thickformwork made from a drilled block that has two openings at the ends ofthe space and the remaining wall therebetween.

Using plastic press forming, such structure is made in a single bodyconfiguration with the light-blocking member 65 and the sensor body 64.

Using the light-blocking member 65 in the sensor body, the reflectedlight that is the light transmitting through the light-emitting lens 58other than the light-emitting lens 58 corresponding to an arbitrallight-emitting member 53 (which is an LED) which turns on the light andis reflected by the fixing belt 35 and the reflected light that isdirectly reflected on the surfaces of the light-emitting lens 58corresponding to an arbitral light-emitting member 52 which turns on thelight or else other light-emitting lens 58 are blocked to directly sothat it is possible to precisely detect the surface condition of thefixing belt 35.

The Seventh Embodiment

In the reflection type optical sensor 42 shown in above each embodiment,as explained in the present embodiment, carrying out sequentialturning-on/off of the light in the light-emitting members 52 such thateach of a plurality of the light-emitting members 52 (which is LEDs)repeatedly turns on and off the light in sequential manor, thereflection type optical sensor 42 can precisely specify the positions ofthe scratches 52 on the surface of the moving body (or a fixing membersuch as the fixing belt 35) in the width direction.

The another interpretation of the “carrying out sequentialturning-on/off of the light of the light-emitting members 52” is, forexample, that each of a plurality of the light-emitting members 52 inthe light emitter unit 75 repeatedly turns on and off the light insequential manner and each light-emitting member 52 repeatedly carriesturning-on/off the light from the right-hand side similar to therepetition as explained above after the light-emitting member 52locating in the most left-hand side in the light emitter unit 75completes to turning-on/off the light in case that the optical spot 46is scanned on the moving body (the fixing belt 35) in the positiveorientation (for example, from left hand side to the right hand side).This is as explained above, due to the relation of the correspondencebetween the light-emitting members 52 in the light emitter unit 75 andthe optical spots made on the moving body (the fixing belt 35) isreverse against the width direction x. Of cause in the embodiments shownin FIGS. 5A to 5D, the sequential turn-on/off of the light in thelight-emitting members 52 is carried out the light-emitting members 52to sequentially turns on/off the light from the left-hand side to theright-hand side.

Once the sequential turning-on/off of the light carried out over all ofthe light-emitting members 52, the sequence is a single cycle. Suchsingle cycle can be repeated in the sequential turning-on/off of thelight explained above.

Carrying out such sequential turning-on of the light, it is possible toscan the optical spot 46 generated on the fixing belt 35 is scanned withthe positive orientation in the width direction x.

The behavior of the light-receiving members 55 (which are PDs) while theoptical spots 46 are scanned with the positive orientation in the widthdirection x is that a plurality of the light-receiving members 55detects the reflected light 47 from the fixing belt 35 synchronous toturning-on of the light at LED(n) that is the n-th light-emitting member52.

For the purpose of the simplicity, assuming the quantity of thelight-emitting members 55 are 2m pieces, then the light detected by thelight-receiving members 55 is done by 2m pieces of the light-receivingmembers 55, where m is an integer. The method of selecting 2mlight-receiving members 55 is explained as follows.

It is not necessary that all of the light-emitting members 52 turningon/off the light from the left side to the right side are used. Anarbitral N″ (N″ is equal to or less than N) pieces of the light-emittingmembers 52 may be used.

When LED(n) which is the n-th light-emitting member 52 turns on thelight, the light-receiving member 55 which receives the maximumintensity of the receiving light among thereof and which receives thesecond maximum intensity of the receiving light are selected.

In most cases, the selected two light-emitting members 55 are adjacentin the arrangement. Assuming the center of the two light-receivingmembers 55 in the width direction be X=0, the rest 2m(2) light-receivingmembers 55 (which is a PD) locating in X=+/−1.51·xP′″ (l=1, 2, . . . ,(m−1)) are selected.

The detected signals 48 that are opto-electronically converted by 2mlight-receiving members 55 and amplified thereafter are sent to thesurface condition judging device 43 upon receipt thereby.

In order to improve the precision of the detection, a method such thatthe detection results obtained from the above sequential turning-on/offof the light is carried out over a plurality of cycles and a process foraveraging of the results of detection is executed.

The sequential turning-on of the light of a plurality in thelight-emitting members 52 (which are LEDs) is controlled by a controlsignal sent from a surface condition judging device 34 (or thecontroller 44).

The Eighth Embodiment

The present embodiment features that, simultaneously turning on aplurality of light-emitting members 52 (which are LEDs) forsimultaneously making a plurality of the optical spots 46, the line ofthe optical scanning in a single cycle in the width direction x isshortened.

For example, assuming the quantity of the light emitter units 75 be 9pieces and the light emitter unit 75(1), the light emitter unit 75(2), .. . , the light emitter unit 75(9) be arranged in the positiveorientation of the width direction x, the light-emitting members 52(which are LEDs) of the light emitter unit 75(2) to the light emitterunit 75(8) turning-n the light when the surface condition of the movingbody (or the fixing member as the fixing belt 35) is detected. In eachlight in emitter unit 75, the light-emitter unit 52(2) is furtherarranged as an order of LED(1), LED(2), LED(3) and LED(4) in thepositive orientation in the width direction x. The light-emitting member52(3) of the light emitter unit 75(2) is called light-emitting memberLED(2-3).

FIG. 15A shows the distribution of the detection output from pluralityof the light-receiving members 55 (which are PDs). The detection outputis normalized as unity against the maximum value. The detections outputfrom the light-receiving members 55 as (PD_(—)1) to (PD_(—)4) and thoseas (PD_(—)15) to (PD_(—)18) are zeros. Therefore, ten pieces of thelight-receiving members 55 receive the reflected light 47 whenlight-emitting member LED(2-3) (or LED2-2) turns on.

When two of the light-emitting members 52 simultaneously turn on thelight, it is necessary that the reflected light 47 due to otherlight-emitting members 52 turning on the light is not detected by theten pieces of the light-receiving members 55 which are used forobtaining the detection results.

Therefore, it is necessary that two light-emitting remembers 52separating in a certain range each other in the width direction x haveto turn on the light when a plurality of light-emitting members 52simultaneously turn on the light.

FIG. 15B shows the detection output of a plurality of thelight-receiving members 55 when light-emitting members LED(2-3),LED(5-3) and LED(8-3) simultaneously turn on the light.

Three of the detection outputs, each similar detection output to that inthe case that a single light-emitting member 52 turns on the light isobtained by three light-emitting members 52 each separated in long rangesimultaneously turn on the light. For the embodiment shown in FIG. 15B,it is understandable that the light-emitting member 52 (named as LED(1))of the light emitter unit 75 (named as LED(2, 5, 8), the light-emittingmember 52 (named as LED(2)) of the light emitter unit 75 (named asLED(2, 5, 8)9, the light-emitting member 52 (named as LED(3)) of thelight emitter unit 75 (named as LED(2, 5, 8)9 and the light-emittingmember 52 (named as LED(4)) of the light emitter unit 75 (named asLED(2, 5, 8)) can simultaneously turn on the light, the light-emittingmember 52 (named as LED(1)) of the light emitter unit 75 (named asLED(3, 6)), the light-emitting member 52 (named LED(2)) of the lightemitter unit 75 (named as LED(3, 6)), the light-emitting member 52(named as LED(3)) of the light emitter unit 75 (named as LED(3, 6)) andthe light-emitting member 52 (named as LED(4)) of the light emitter unit75 (named as LED(3, 6)) can simultaneously turn on the light and thelight-emitting member 52 (LED(1)) of the light emitter unit 75 (named asLED(4, 7)), the light-emitting member 52 (named as LED(2)) of the lightemitter unit 75 (named as LED(4, 7)), the light-emitting member 52(named LED(3)) of the light emitter unit 75 (named as LED(4, 7)) and thelight-emitting member 52 (named LED(4)) of the light emitter unit 75(named as LED(4, 7)) can simultaneously turn on the light.

It is possible to shorten the single cycle of the optical scanning linein the width direction x by simultaneously turning on the light of aplurality of the light-emitting members 52 separated in enough rangeeach other. Then it is possible to shorten the time necessary forforming an image since the conveying speed of the fixing bet 35 isincreased due to the shortening of the line cycle time.

It is preferable the light emitter unit 75 is constructed in accordanceto the relation with the light-emitting members 52 simultaneouslyturning on the light. For example, the light-emitting members 52 thatare in the same arrangement even for the different light emitter units75 simultaneously turn on the light. The light-emitting members 52 thatare in the same arrangement in the light emitter units 75 placing everytwo units simultaneously turn on the light such that the samelight-receiving member 55 does not simultaneously detect a plurality ofthe reflected light beams 47.

The control of a plurality of the light-emitting members 52 (LED)simultaneously turning on the light is carried out by the control signalsent from the surface condition judging device 43 (or the controller44).

The Ninth Embodiment

The present embodiment features that the optical spots 46 are generatedwith a arbitral tilted angle against the width direction x and themoving direction y as shown in FIG. 16B in contrast to that the opticalspots 46 are generated along with the width direction x for the movingbody (the fixing members as the fixing belt 35) in each embodimentpreviously discussed as shown in, for example, FIG. 16A.

The optical spots 46 tilting to the width direction x, it is possible toreduced the arrangement pitch of the optical spots 46 in the widthdirection.

More concretely, the reflection type optical sensors 42 are tiltedagainst the width direction x and the moving direction y in the presentembodiment in contrast that the reflection type optical sensors 42 arearranged in the direction of the width direction x in each of theprevious embodiments.

The reflection type optical sensors 42 tilting to the width direction xand the moving direction y, it is possible to reduce the arrangementpitch of the optical spots 46 in the width direction.

In FIG. 16B, the reflection type optical sensors 42 are tilted with 45degrees against the width direction x.

The reflection type optical sensors 42 being tilted with 45 degrees, thereflection type optical sensors 42 has better resolution of position inthe detection results in comparison to the reflection type opticalsensors 42 not being tilted since the arrangement pitch can be as littleas 1/square root 2 times though the length of the width direction of thedetection region A′ is shortened to be 1/square root 2 times for thecase of no tilting.

The tilting angle of the reflection type optical sensors 42 is notlimited as that explained, smaller angles such as 0 degree to 45 degreesor larger angles as 45 degrees to 90 degrees are arbitrarily selected.The reflection type optical sensors 42 can be tilted to left downinstead of right down of the schematic as shown in FIG. 16B.

The optical spots 46 are tilted by the reflection type optical sensors42 themselves being tilted as explained above, however, other than suchtiling, the light-emitting members 52 may be set in tilt angle in thereflection type optical sensors 42 with the arrangement that thereflection type optical sensors 42 is, for example, placed in parallelto the width direction x, or the light 45 may be deflected by using thelight-emitting lenses 58 so that the arrangement pitch of the opticalspots 46 in the width direction x is made smaller than the spacingbetween the light-emitting members in the arrangement direction.

In addition to the above tilting, the reflection type optical sensors 42wherein the optical spots 46 are tilted are set by using thelight-emitting members 52 further tilted in the reflection type opticalsensors 42 or the light 45 deflected in use of the light-emitting lens58.

When the light-emitting members 52 further are set with a tilting anglein the reflection type optical sensors 42, every light emitter systems(or the light emitter unit 75) can be set in a tilting angle.

The Tenth Embodiment

In the present embodiment, the reflection type optical sensors 42 areinstalled in the inside of the image generation apparatus 1 (see FIG.1).

By setting the reflection type optical sensors 42 in the imagegeneration apparatus 1, the detection of the scratches 51 on the movingbody (or the fixing members as the fixing belt 35) in a real-time, whichhad been impossible before the present invention disclosed, and thedetection of the position and the width of the scratches 51 on thefixing belt 35 are possible.

As explained in each above embodiment, optimizinglight-receiving/emitting device (such as the light-emitting members 52and/or the light-receiving members 55) for the use in the reflectiontype optical sensors 42 and optical system (light-emitting opticalsystem 53 and light-receiving optical system 56) for use of thereflection type optical sensors 42, it is possible to improve theprecision of the detection of the scratches 51 on the surface of thefixing belt 35 by increasing the intensity of the reflected light 47from the fixing belt 35 with keeping the spacing of the adjacent opticalspots 46 on the moving body (the fixing member as the fixing belt 35).

The Eleventh Embodiment

In the present embodiment, the reflection type sensors 42 are set nearthe width periphery position 35 s of the small size blanks (recordingmedia S) in the image generation apparatus 1.

When the length of the detection region A in the width direction isshortened, it is possible to include the width periphery position 35 sof the blanks in the detection region A.

There is a merit to make it possible to compact the reflection typeoptical sensors 42 especially in the width direction x due to enablingto shorten the detection region A.

The widths of the scratches 51 being generally in the range of severalhundreds of microns to several millimeters, the preferred length of thedetection region A is 5 mm to 15 mm in the width direction x for thepurpose of compacting the reflection type optical sensors 42.

It is possible to generally use a plurality size of the blanks such asA3, A4 and A5 for the image generation apparatus 1.

As a concrete example, the maximum size of the blanks is mostly the A3size paper laid in longitudinal direction, smaller size blanks meanthose small than A3 size.

If the image generation apparatus 1 can process the A2 size paper laidin longitudinal direction as the maximum size of the blanks, smallersize blanks mean those small than A3 size.

The reflection type optical sensors 42 can be set at the width peripheryposition 35 s of the blanks which is the maximum size paper laid inlongitudinal direction in the construction of the image generationapparatus 1.

Since there are two positions on the paper for the width peripheryposition 35 s of the small size blanks, the reflection type opticalsensors 42 can be placed each to each of both width peripheries of theblank, in other words two of the reflection type optical sensors 42 inthe width direction x therefore the scratches 51 are made in bothperiphery sides of the blanks. However, since there is no largedifference of the longitudinal streak scratches 51, which are due toboth end surfaces of the blanks are evenly generated in both sides ofthe blanks, in between one side of the width ends and the other sidethereof, it is satisfactorily enough to have the reflection type opticalsensor 42 in either side thereof.

The Twelfth Embodiment

The present embodiment, the reflection type optical sensors 42 areenlarged to the width direction x in order to cover various size ofblanks, as shown in FIG. 18.

When widening the refection type optical sensors 42 in the widthdirection, the image generation apparatus 1 can process A2, A3, A4, A5,B3, B4, B5 and B6 size blanks since the width periphery position 35 s ofall such size can be exposed to be irradiated by the reflection typeoptical sensors 42.

The Thirteenth Embodiment

In the present embodiment, the fixing belt 35 is used for the movingbody.

By using the fixing belt 35 as the moving body, it is possible toprecisely detect the surface condition of the fixing belt 35 using thereflection type optical sensors 42 as shown in the present invention.

A fuser roller 31 can be used for the moving body.

In addition, the embodiment of the reflection optical detection devicein the above embodiment is not limited in the reflection type opticalsensors shown in the above embodiments but those enabling to detect thereflect light are usable.

Though the reflection type optical sensors as described in the aboveembodiments have an array including a plurality of LEDs and a pluralityof PDs which oppose each other, another structure of the reflection typeoptical sensor such that the laser beam out coming from thelight-emitting members are deflected by optical defectors and one or aplurality of PDs receiving the laser beam which reflects on the fixingbelt 35 can be used. As another preferred embodiment, a structure of theimage generation apparatus wherein a reflection type optical sensorincluding an LED and a PD is driven to scan the primary direction of thefixing belt 35 can be used.

The detail technologies to accomplish the second purpose of the presentinvention are discussed in the following paragraphs.

The reflection type optical sensors regarding the present invention isused for an image generation apparatus and comprises reflection typeoptical sensors to detect the surface conditions of a moving bodyincluding a plurality of light emitter systems that have light-emittingmembers and a light-emitting optical system that have a plurality oflight-emitting lenses and a light-receiving device including a lightreceiver systems that have light-receiving members receiving reflectlight reflected on a moving body and light-receiving optical systemsthat have light-receiving lenses corresponding to the light-receivingmembers.

By forming the light-emitting lenses and the light-receiving lenses intoa single element, the precision of the physical arrangement of each lensagainst each other one can be improved as well as improvement of theworkability regarding the assembly of each lens. In such assemblyprocess, it is preferable to form all of the light-emitting lenses andthe light-receiving lenses into a single element. It is also preferableto compose a plurality of the single elements into which some of thelight-emitting lenses and the light-receiving lenses are formed.

A plurality of the light-emitting lenses and the light-receiving lensesare aligned such that the centers of lenses are deviated from theoptical axis. Using such alignment, it is possible to suppress theoutput variation of the light-receiving member resulting from angledeviation (especially the deviation of elevation angle) of the movingbody against the reflection type optical sensors.

Setting a planner portion parallel to the optical axis at the borderbetween the light-emitting lens and the light-receiving lens, the light(called “ghost light” hereinafter) other than that is necessary todetect the surface condition of the moving body can be reduced.Therefore the reflection type optical sensors regarding the presentinvention is excelling in the optical performance, preferred to be ableto be used for the image generation apparatus etc. The “planner portionparallel to the optical axis” does not imply only the exact parallel tothe optical axis but also substantively parallel thereto regardless toexistence of unlevel surface of the planner portion, slight gradient inthe parallelism etc. As will be explained, the major feature such thatthe ghost light other than that is necessary to detect the surfacecondition of the moving body is reduced is only preferred functionthereof.

It is preferred that the light-emitting members of the light emittersystems are set to substantially have surface symmetry to the surfacethat includes the optical axis of the light-emitting lens correspondinglight-emitting lens. By using such construction, it is possible toradiate the light with a substantially equal separation distance on thesurface of the moving body. The surface symmetry is not exact one butincludes substantive symmetry.

It is preferred that the reflection type optical sensors in the presentinvention is designed such that the light-receiving lenses are locatedfarther for the light-receiver system for the optical axis in comparisonto the light-emitting lenses. It is possible to make the curvatureradius of the light-receiving lenses large by setting thelight-receiving lens for the optical axis of the lens largely apart fromthe light emitter system. As the result, especially in the case when themoving body is especially a fixing member to fix the images, the outputvariation of the light-receiving members of the reflection type opticalsensors due to the deviations of elevation angles of the fixing memberscan be preferably reduced.

For the reflection type optical sensors regarding the present invention,the light-receiving lenses are preferably cylindrical lenses thatconvert the light into an axial line. Using a single cylindrical lensesfor the light-receiving lenses, the deviation of lens parameters (forexample, curvatures of the lens radius, lens positions, lensthicknesses, etc.) among lenses can be removed, therefore it is possibleto detect the surface conditions of the moving body.

Using cylindrical lenses that have no optical effects in the primaryscanning direction for the light-receiving lenses, the deviation of theintensity distribution of the received light by the light-receivingmembers caused by the difference of the light emitter systems that turnon the light can be suppressed in comparison to the use of sphericallenses for the light-receiving lenses.

For the reflection type optical sensors regarding the present invention,it is preferred to set an open-end space between the light-emittingsystem and the light-emitting optical system. By setting the open-endspace which is surrounded by a light-blocking surrounding wall, it ispossible to prevent direct incidence of i) the light emitted through thelight-emitting lenses other than the light-emitting lens correspondingto an arbitral light emitter system that turns on the light and ii) thedirectly reflected light on the surfaces of the light-emitting lensesother than that corresponding to the light emitter system that turns onthe light (such directly reflected light is called “flare” hereinafter).Therefore, it is possible to precisely detect the surface condition ofthe moving body. In order to make such an open-end space, it is possibleto use a step of a planner portion as the reference, the accuracy of theposition thereof and the optical performance of the reflection typesensor can be improved.

It is preferred that the reflection type optical sensors regarding thepresent invention are to radiate the light to sequentially generate theoptical spots on the surface of the moving body. Sequentially making aplurality of the optical spots, cross talk (a light-receiving membersimultaneously receives the each reflected light reflected by each of aplurality of the light emitter systems) is removed in comparison to thecase to simultaneously radiate the light to generate the optical spotsat once.

The reflection type optical sensors of the present invention may havesuch a structure that the light-emitting members of a plurality of thelight emitter systems may radiate light to simultaneously generate theoptical spots on the moving body. Simultaneously generating a pluralityof the optical spots, it is possible to shorten a line cycle (that isthe time necessary to make all light emitter systems turning on thelight). In order to detect the surface condition in a short time, it ispossible to remove a missing detection to surely detect the scratches ofthe surface of the moving body. The light radiation in sequentiallygenerating the optical spots is preferably selected to be effective tothe purposes of the reflection type optical sensors, depths and/orwidths of scratches, the environment conditions under which thereflection type optical sensors are used.

For the reflection type optical sensors of the present invention, it ispreferable that a plurality of the optical spots is generated from theradiation from the light-emitting members of a plurality of the lightemitter systems with arbitral angle against the detection direction ofthe surface of the moving body. For this purpose, the light emittersystems are aligned with a tilt angle against the detection direction ofthe moving body, in other words a tilt angle against the primaryscanning direction or the optical spots are radiated in a line ofarrangement thereof with a tilt angle even under the parallel alignmentof the light emitter systems to the primary scanning direction. Thearrangement pitch of the optical spots is different between the casethat the optical spots are generated in a line parallel to the primaryscanning direction and the case t the optical spots are generated in aline parallel to the primary scanning direction. It is possible to makethe arrangement pitch of the optical spots relatively small in the casethe optical spots are generated in a line parallel to the primaryscanning.

The reflection type optical sensors regarding the present invention maybe placed at or near the periphery end position of the recording mediacarried by the moving body or placed over the full width of therecording media. In such arrangement of the reflection type opticalsensors, it is possible to compact the reflection type optical sensorssince the detection region including the end portion can be small sothat it is possible to easily improve the position resolution.

It is preferable that the length in the arrangement direction of aplurality of the light emitter systems is same as that of the length ofmoving body in the arrangement direction for the reflection type opticalsensors regarding the present invention. In such construction, it ispossible to have length of the reflection type optical sensors in theprimary scanning direction long enough to process various sizes ofblanks and surely detect the scratches even made at the differentpositions on the moving body due to the difference of the sizes of theblanks. The length in the arrangement direction of a plurality of thelight emitter systems can be substantively same as that of the length ofmoving body in the arrangement direction for the reflection type opticalsensors so that the detection of the scratches can be sufficientlycarried out.

In the image generation apparatus of the present invention, thereflection type optical sensors as explained above of the good opticalproperties is used as the reflection type sensors that detect thesurface conditions of the moving body to fix the image on recordingmedia. Therefore, it is possible to precisely detect the surfacecondition and keep high precision image quality. Also it is possible toprovide the image generation apparatus that can keep low maintenancecost since the exchange of the moving body is not frequently required.

For the image generation apparatus in the present invention, it ispreferred that the moving bodies are fixing belts which have noperipheries. Since surface materials such as PFA (a trade mark ofperfluoroalkoxy) or PTFE (a trademark of polytetrafluoroethylene) areused, the surface of fixing belt can easily get scratches in extremefrequency. However, using the reflection type optical sensors aspreviously explained in the present invention, it is possible to quicklydetect the occurrence of the scratches with precise surface detection ofthe fixing belt. Therefore, it is possible to make such a countermeasurethat the recording media do not pass through the region where thescratches exist on the surface of the fixing belt and therefore to usethe fixing belt with good efficiency in terms of extending the term toexchange the fixing belts.

In addition to the first embodiment to the twelfth embodiment asexplained above, further embodiments that are to achieve the secondpurpose of the present invention are explained in the followingdiscussion.

The Fourteenth Embodiment

The fourteenth embodiment of the image generation apparatus of thepresent invention is explained referring to schematics. The presentembodiment shows an example using a full color printer with tandemstructure (simply called a “printer” hereinafter) to which the imagegeneration apparatus is applied. The image generation apparatus in thepresent invention is not confined in color printers but also includecopy machines, facsimile terminals, printing machines and complexmachines that combine these functions. The printer in the presentembodiment is to form images by using four toners such as a yellow, acyan, a magenta and a black toners for which the image generationapparatus equips each member corresponding thereto. The members used fora yellow color, a cyan color, a magenta color and a black color aredenoted with letters Y, C, M and BK at the numbers assigned to themembers.

As shown in FIG. 19, a tandem structure including photo receptor drums20Y, 20C, 20M, 20BK as image carrier holders. Each of these photoreceptor drums 20Y, 20C, 20M, 20BK can form each image corresponding tothose decomposed in to yellow, cyan, magenta or black color.

The structure of the printer 100 of the present embodiment is explainedin the following. As shown in FIG. 19, the printer 100 comprises fourimage stations 1Y, 1C, 1M and 1BK that carries out the process ofcharging and developing for colors as yellow, cyan, magenta and blackcorresponding to photo receptor drums 20Y, 20C, 20M, 20BK, respectively,an optical scanning device 408 for exposing device (that is opticalwriting device), an image transfer member such as an image transferringbelt unit 410 and a secondary image transferring roller 5, anintermediate image transferring belt cleaning device 413, a fixing unit406 for a fixing member, a reflection type optical sensor 200 as thereflection type optical detection device and a surface condition judgingdevice 300 (see FIG. 20).

The printer 100 further comprises a sheet supply device 480 as a papersupply cassette to supply recording papers S as recording media, a pairof resist rollers 404 that convey the recording papers S a sensor (notshown in the figures) that detects the arrival of the front edge of therecording papers S at a pair of the resist rollers 404. The sheet supplydevice 480 carries recording papers conveyed toward between photoreceptor drums 20Y, 20C, 20M, 20BK and an image transferring belt 411 tobe explained later. A pair of resist rollers 404 sends the recordingpaper S carried by the sheet supply device 480 to meet a predeterminedtiming to form toner images by the image stations 1Y, 1C, 1M and 1BK tothe transferring portion between each photo receptor drums 20Y, 20C, 20Mor 20BK and an intermediate image transferring belt 411.

The printer 100 comprises a paper ejecting roller 407 that dischargesthe recording papers S that have been processed to fix the images tooutside the main body of the printer 100, a paper ejecting tray 417,toner bottles 9Y, 9C, 9M and 9BK. The fixing unit 406 is to fix thetoner image transferred to the recording paper S. The paper ejectingtray 417, being set in the upper part of the printer 100, carries therecording paper S ejected out from the printer 100 by the paper ejectingroller 407. The toner bottles 9Y, 9C, 9M and 9BK, being placed under thepaper ejecting tray 417, are filled with yellow toner, cyan toner,magenta toner and black toner, respectively.

The image transferring belt unit 410, being opposingly placed above thephoto receptor drums 20Y, 20C, 20M and 20BK, have the intermediate imagetransferring belt 411 and the primary image transferring roller 12Y, 12M12C and 12BK. The secondary image transferring roller 405 is an imagetransferring roller opposed to the intermediate image transferring belt411 and rotates in accordance with the rotation of an intermediate imagetransferring belt 411. The intermediate image transferring belt cleaningdevice is set against the intermediate image transferring belt 411 andcleaning the surface of the intermediate image transferring belt 411.The optical scanning devices 408 are set opposingly under the four imagestations 1Y, 1C, 1M and 1BK.

The image transferring belt units 410 includes a driving roller 472 towhich the intermediate image transferring belt 411 is engaged and aslave roller 473 as well, other than the intermediate image transferringbelt 411 and the primary transferring rollers 12Y, 12C, 12M and 12BK.

The slave roller 473 has a function to add further tension to theintermediate image transferring belt 411. For this purpose, the salveroller 473 equips an additive tension device using springs. The secondimage transfer member 471 is constructed with such image transferringbelt unit 410, the primary image transferring rollers 12Y, 12, C, 12Mand 12BK, the secondary image transferring roller 405 and theintermediate image transferring belt cleaning device 413.

The intermediate image transferring belts 411, that is the first imagetransfer member (and working as the second image holding carrier), areplaced at the positions corresponding to the photo receptor drums 20Y,20C, 20M and 20 BK and visible images formed on the photo receptor drums20Y, 20C, 20M and 20 BK transferred thereon can move toward the arrowsign A1 in FIG. 19. An endless belt is used for the intermediate imagetransferring belt 411. In the first transferring process, images aretransferred in a superimposing manner onto the intermediate imagetransfer belt 411, wherein the images are batch-transferred to therecording papers used for the recording sheets via the secondarytransferring process by using the second image transfer member 471.

The images being transferred in a superimposing manner to theintermediate image transferring belt 411 implies that each of thevisible images formed on the photo receptor drums 20Y, 20C, 20M and 20BKis transferred to the same portion of the intermediate transferring belt411 in an overlapping. For enabling such a transferring in asuperimposing manger, each of the primary image transferring rollers 12,12C, 12M and 12BK is place opposing to each of the photo receptor drums20Y, 20C, 20M and 20BK via the intermediate image transferring belt 411.The image transfer using the primary image transferring roller 12Y, 12C,12M and 12BK from the upper stream side to downstream side in the A1direction by applying voltages with different timing.

The details being omitted to explain, the intermediate imagetransferring belt cleaning device 413 installed in the second imagetransfer member 471 opposes to the intermediate image transferring belt411 and includes a cleaning brush and a cleaning blade. The cleaningbrush and the cleaning blade clean the intermediate image transferringbelt by striping to remove staying foreign materials such that residualtoners etc. The intermediate image transferring belt has a dischargedevice (not shown in the figures) to bring out to dispose the removedresidual toners.

As explained above, the printer 100 as shown in FIG. 19 has such afunction that the color image superimposed is batch-transferred to therecording paper S via the secondary image transferring roller 405 bytransferring the color images formed on photo receptor drums 20Y, 20C,20M and 20BK each by each. However, the image generation apparatusregarding the present invention is not limited to the structure shown inthe present embodiment but the structure such that the intermediateimage transferring belt 411 holds the recording papers S and each colorimage on each of photo receptor drums 20Y, 20C, 20M and 20BK is directlysuperimpose to the recording papers S can be adopted.

The photo receptor drums 20Y, 20C, 20M and 20BK that generate images ofyellow color, cyan color, magenta color and black color, respectivelyare arranged in this order from the upper stream of A1 paper passing.Around the photo receptor drums 20Y, 20C, 20M and 20BK, an imagestations 1Y, 1C, 1M and 1BK that apply electrostatic-charging thereonand develop the images in the order of the rotation of photo receptordrums are placed. As the image station 1Y, 1C, 1M and 1BK, anelectrostatic-charging device 30Y, 30C, 30M and 30BK, a developingdevice 40Y, 40C, 40M and 40 BK, a primary image transferring roller 12Y,12C, 12M and 12BK and a cleaning device 50Y, 50C, 50M and 50 BK areplaced in the rotation direction of the photo receptor drums 20Y, 20C,20M and 20BK. For WRITE after electrostatic-charging, an opticalscanning device 408 is used.

The optical scanning device 408 includes semiconductor laser devices,coupling lenses, f-theta lenses, toroidal lenses, mirrors and rotationalpolygon mirrors. The coupling lenses are to convert the laser light into substantially parallel beams (called writing light Lb hereinafter).The writing light Lb is scanned by the mirrors of the polygon mirror inaccordance to the rotation thereof and forms the optical spots on thesurface of the photo receptor drums 20Y, 20C, 20M and 20BK via Ethetalenses, toridal lenses and mirrors. The optical spots move in thelongitudinal direction on the surface of the photo receptor drums 20Y,20C, 20M and 20BK to scan the surface thereof. The optical scanningdevice 408 emits the writing light Lb to corresponding each of the photoreceptor drums 20Y, 20C, 20M and 20BK and make an electrostatic latentimage on the surface each thereof.

The sheet supply device 480 is set under the main body of the printer100 and has convey roller 3 which contacts to the upper surface of therecording paper S. The recording paper S in the upper most position isconveyed to a pair of the resist roller 404 by driving to rotate theconvey roller 3 in the counter clock wise.

For the fixing unit 406, a method of belt fixing is adopted. The systemfor such method comprises a fixing belt 461 (or 35), a heating roller462 around which the fixing belt 461 is wrapped, a pressing roller 463which opposes to the pressing roller 463 and a fuser roller 464 aroundwhich the fixing belt 461, opposing to the pressing roller 463, iswrapped. The detail structure of the fixing unit 406 is explained asfollows.

FIG. 20 shows the structure of the fixing unit 406. As shown in FIG. 20,the fixing unit 406 comprises the pressing roller 463 as a pressurizingbody, the fixing belt 461 as a moving body, the heating roller 462around which the fixing belt 461 is wrapped, the fuser roller 464 aroundwhich the fixing belt 61, opposing to the pressing roller 463, iswrapped, a tension roller 465 which adds tension to the fixing belt 464,a thermal sensor (not shown in the figures) to detect the temperature ofa separation click 467 set at the downstream in the carrying directionof the recording paper S position at a nipping part and that of thefixing belt 461 on the heating roller 462.

The pressing roller 463 has an elastic layer made of silicon rubber etc.on the surface of a rod made of aluminum or iron etc. and a peel plymade of PFA or PTFE. The fixing belt 461 is a base material made ofnickel or polyimide with a peel ply such as a surface layer of PFA orPTFE formed further thereon or that has further an intermediate elasticlayer of silicon rubber between the base material and the surface layer.The fixing belt 461 is engaged to both the fuser roller 464 and theheating roller 462 which rotate therewith and keeps appropriate tensionby externally pushing with the tension roller 465. The fuser roller 464has a metal rod and a silicon rubber covering the surface thereof. Theheating roller 462 has a hollow tube made of aluminum or iron and a heatsource H such as halogen heater inside thereof.

The fixing unit 406 composing with these materials and elements formsthe nipping part 466 that holds and carries the recording paper S. Oncethe recording paper S comes to the nipping part 466 from the downsideand the image is fixed onto recording paper S by applying apre-determined pressure and heat at the nipping part 466.

The tension roller 465 has silicon rubber on the surface of a metal rod.The separation click 467 has a sharp front edge facing and contacting tothe surface of the fuser roller 464. A plurality of the separationclicks 467 are arranged in the direction of the axis (vertical directionfrom the page surface) of the fuser roller 464. The fixing unit 406 hasa non-contacting thermal sensor (such as thermopile) as thermal sensorthat monitors the temperature in non-contact to the fixing belt 461. Thepresent invention is not limited to use such thermal sensor but acontacting thermal sensor (such a thermistor) that contacts with thefixing belt 461.

As shown in FIG. 22, carrying out to repeat the fixing process for theA4 size paper laid in longitudinal direction using the fixing unit 406,longitudinal streak scratches are made at the positions, on the surfaceof the fixing belt 461, which are the longitudinal end peripheries of A4conventional paper. Such streak scratches are made due to paper debristhat is attached to both end peripheries of the paper and abrades thesurface of the fixing belt 461. When a fixing process is carried outusing A4 and/or A3 size paper laid in transverse direction, grazingstreak comes out to the surface of the image corresponding to suchlongitudinal streak scratches. The appearance of this grazing streakdegrades the quality of printed images.

In order to solve this problem, the surface condition of the fixing belt461 is judged by using the reflection type optical sensors 200 and thesurface condition judging device 300. FIG. 21 shows the arrangement ofthe reflection type optical sensors 200 and the surface conditionjudging device 300. The reflection type optical sensors 200, as shown inFIG. 21, is placed in opposing to the fixing belt 461 on the heatingroller 462.

The reflection type optical sensors 200 radiates the light and forms theoptical spots in the primary scanning direction toward the surface ofthe fixing belt 461 and detect the reflected light from the fixing belt461. The surface condition judgment device 300, being connected to thereflection type optical sensors 200, the judges the surface condition ofthe fixing belt 461 by receiving the detection signal from thereflection type optical sensors 200.

For the surface condition judging device 300, a main body controllerdevice can be used to drive and control each portion or member of theprinter 100. The main body controller device includes a CPU (a centralprocessing unit) that executes various operations and drives andcontrols the portions of the printer 100, ROM (Read Only Memory) thatstores fixed data such as computer executable programs, RAM (RandomAccess Memory) that functions as a working area of the data to freely bewritten or rewritten. The present invention is not limited to such asystem construction but a separated controller device other than thoseinstalled in the main body is usable for the surface condition judgingdevice 300.

FIG. 22 is a schematic to explain the status when longitudinal streakscratches in a view from the direction vertical to the axis (the primaryscanning direction) of the heating roller 462. As shown in FIG. 22, asingle device of the reflection type optical sensors 200 is, in theprimary scanning direction on the fixing belt 461, set at the side ofthe end edge (called “edge portion” hereinafter) of the width directionof the blanks set in an A4 longitudinal-laid direction. The reflectiontype optical sensors 200 form a long detection region A on the fixingbelt 461 by radiating the light to form a plural of the optical spots.According to such setting up, it is not necessary to rigorously keep therelative positional relation between the reflection type optical sensors200 and the edge periphery portion of the blanks in the primary scanningdirection since the reflection type optical sensors 200 form such a longdetection region A.

The surface condition judging device 300 can detect the surfacecondition of the detection region A, which is long in the primaryscanning direction, by receiving the detection signals from thereflection type optical sensors 200. When the edge portion of the blanksis included in the detection region A, the levels and/or the positionsof longitudinal streak scratches made at the edge periphery portion ofthe blanks is, for the purpose of quantification, defined as the surfaceconditions of the fixing belt 461. The details for the quantificationwill be explained later. The levels of scratches represents the degreeof the scratches, so that implies the depths (or roughness) and widths(magnitudes) of the scratches.

(Structure of the Reflection Type Optical Sensors)

The principal structure of the reflection type optical sensors 200 (or200 a) regarding the fourteenth embodiment is shown in FIGS. 23A and23B. The x direction is the primary scanning direction of the fixingbelt 461, the y direction is the secondary scanning direction, z is adirection vertical to the x-y plan and the direction of the reflectiontype optical sensors 200 a directs an opposing direction to the fixingbelt 461. The relation of the relevant directions is same as in thefollowing embodiments or the examples for comparison.

FIG. 23A is a schematic cross-sectional view of the reflection typeoptical sensor regarding the fourteenth embodiment observed in theprimarily scanning direction. As shown in FIG. 23A, the reflection typeoptical sensors 200 a regarding fourteenth embodiment comprises alight-emitting diode (called an LED hereinafter) 211 a, a light-emittingoptical system having light-emitting lenses 221 a arranged to guide theemitted light to the fixing belt 461 and generate optical spots SP,light-receiving lenses 222 a guiding the reflected light reflected bythe fixing belt 461, a light-receiving optical system having photodiodes (called PDs or a PD for a singular hereinafter) 212 a, a board210 a supporting the LED 211 a and a PD 212 a and a case 240 a to holdthe board 210 a and the lens array 220 a. At the boarder portion of thelight-emitting lenses 221 a and the light-receiving lenses 222 a, a step223 a is formed at the planner portion parallel to the optical axis.

A lens array 220 a is an element made in such a way that plurality oflight-emitting lenses 221 a and a single light-receiving lens 222 a arearranged in two dimensional arrays and formed into a single element.

FIG. 23B is a schematic cross-sectional view of the reflection typeoptical sensor shown in FIG. 23A in the secondary scanning direction (ydirection). FIG. 24 is a schematic cross-sectional view of the PD 212 aand the light-receiving lenses 222 a used for the reflection typeoptical sensors 200 a observed in the secondary scanning direction (ydirection). FIG. 25 is a schematic of the details of the light-emittinglenses 221 a and the light-receiving lenses 222 a. FIG. 26 is aschematic plan view of a board that supports an LED 211 a and the PD 212a. For the cross-sectional views as shown in FIGS. 23A, 23B and 24, theportion in the front page surface of the case 240 a is removed and theportion of the back side is omitted. Same removal and omission are takenplace in the following embodiments.

As shown in FIGS. 23A and 26, the plurality of LED 211 a is placed inthe primary scanning direction. One light-emitting lens 221 acorresponding to the four LEDs 211 a are placed. The lens diameter inthe primary scanning direction of the light-emitting lens 221 a is 2.4mm. The arrangement pitch of the four LEDs 211 a is P (see FIG. 26). Asshown by a dotted line in FIG. 23B, four LEDs 211 a emits light of whichbeams are symmetry against the optical axis of the light-emitting lenses221 a. In the present embodiment, the light from the first LED and thelight from the fourth LED are symmetry against the optical axis and thelight from the second LED and the light from the third LED are symmetryagainst the optical axis as well. Therefore it is possible to generatethe optical spots SP as those in a train with substantially equivalentdistances (or distance P″) on the surface of the fixing belt 461.

When the surface condition of the fixing belt 461 is detected in thereflection type optical sensors, the distance or the angel of thesurface of detection against the reflection type optical sensors 200 aare deviated due to ruffling, floppy or curling of the fixing belt 461.It is difficult to completely remove such deviation. Therefore, there isa problem that precise detection is scarcely possible since the outputof detection signal does not reflect the correct output to detect thesurface condition of the fixing belt 461. Especially there is a problemthat the influence of the variation of angles due to the surface waving(called “waving angle” hereinafter) is remarkably large.

For the reflection type optical sensors 200 a regarding the fourteenthembodiment, anamorphic lenses that have different optical power ratiofor the primary scanning direction and the secondary scanning directionis adopted as shown in FIGS. 23A and 23B. Using anamorphic lenses, it ispossible to optimize the curvature radii of the lenses in secondaryscanning direction with keeping the spot diameter of optical spot SP(therefore a diameter of the optical beam thereof) in a predeterminedcondition on the fixing belt 461. Therefore, it is possible to decreasethe fluctuation of the output of the light-receiving members when thewaving angle due to the surface waving of the fixing belt 461. As theresult, it is possible to avoid the degradation of the precision of thedetection using the reflection type optical sensors 200 a and keep goodoptical characteristic thereof.

The reflection type output sensors 200 a in the fourteenth embodimenthave following three differences against the reflection type opticalsensors 200′ that will be explained later, wherein the second item (2)is the major feature thereof.

That is

-   (1) no light-blocking surrounding walls are used,-   (2) the light-emitting lenses 221 a and the light-receiving lenses    222 a are placed to have different optical axes,-   (3) the lens parameters (as curvature radii, lens diameters, lens    thicknesses, the center-to-center distance between the    light-receiving system and the light-emitting lens and the    center-to-center distance between the light-receiver system and the    light-receiving lens)) are different.

The light-emitting lenses 221 as mentioned in (1) and thelight-receiving lenses 222 a are different of 0.25 mm regarding the lenscenter in the direction of the optical axis, therefore thelight-emitting lenses 221 a are placed closer to the light emittersystems (the LED 221 a) in the optical axis direction.

To concretely explain the lens parameters, the curvature radius of thelight-emitting lenses 221 a is 4.6 mm in the primary scanning direction,a conical constant is 0 in the primary scanning direction. The curvatureradius and conical constant of the light-emitting lenses 221 a is 4.3 mmand −2.0 in the secondary scanning direction, respectively, thediameters of the light-emitting lenses 221 a are 2.4 mm and 9.2 mm inthe primary and secondary scanning directions, respectively and thethickness of the light-emitting lenses is 6.6 mm.

The curvature radius of the light-receiving lenses 222 a is 50 mm in theprimary scanning direction, a conical constant is −1.0 in the primaryscanning direction. The curvature radius and conical constant of thelight-receiving lenses 222 a is 4.8 mm and −1.6 in the secondaryscanning direction, respectively, in the secondary scanning direction,the diameters of the light-receiving lenses 222 a are 17 mm and 0.9 mmin the primary and the secondary scanning directions, respectively andthe thickness of the light-emitting lenses is 6.35 mm.

The center-to-center distance of the light-emitting lenses 221 a and thelight-receiving lenses 222 a is 2.53 mm in the secondary scanningdirection. The center-to-center distance between the light-emittingsystems (the LED 211 a) and the light-emitting lenses 221 is 10.37 mm inthe optical axes and the center-to-center distance between thelight-receiver system (the PD 212 a) and the light-receiving lenses 222a is 10.62 mm in the optical axis direction. In such center-to-centerdistances, as mentioned previously, the light-emitting lenses 221 a andthe light-receiving lenses 222 a are different in the lens centerpositions as deviated 0.24 mm.

A combination of four LEDs 211 a and the light-emitting lens 221 a iscalled a unit hereinafter. Placing the plurality of units in the primaryscanning direction, the unit constructs the light-emitting device of thereflection type optical sensors 220 a (such as a light-emitting systemplus a light-emitting optical system). As shown in 26, the arrangementpitch of the unit in the primary scanning direction is P′ and thearrangement of the units is unit 1, unit 2, . . . , unit L from the leftof the page of FIG. 26. Though it is possible to place the plurality ofunits, we confine the quantity of units in seven ones (so that L=7) inthe present embodiment, the following embodiments and the examples forcomparison.

The light emitted from each of LEDs 211 radiates the surface of thefixing belt 461 to generate optical spot SP through the correspondingthe light-emitting lens 221 a. Therefore, the plurality of optical spotsSP is generated on the surface of the fixing belt 461 with anarrangement of pit P″ in the direction of the primary scanning directionas shown in FIG. 23B.

FIG. 24 is a schematic back view of the PD 212 a of the reflection typeoptical sensors 200 a shown in FIG. 23A and the light-receiving lenses222 in a reflection of the secondary scanning direction (y direction).As shown in FIGS. 24 and 26, a plurality of PDP 212 a are arranged inthe primary scanning direction opposing to the LED 211 a, wherein, thearrangement pitch of the primary scanning direction is Pa′″. Thereflection type optical sensors 200 a has a pit Pa′″ (which is thearrangement pitch of the PD 212 a) which is nearly equals to the Pa″(which is the arrangement pitch of optical spot SP) being further nearlyequal to a quarter of the arrangement pitch of the unit.

For the light-receiving lenses 222 a, an anamorphic lens that hasdifferent optical power ratio for the primary scanning direction and thesecondary scanning direction is used. When the optical spots SP isgenerated on the surface of the fixing belt 461 in the primary scanningdirection when the light is emitted from the LED 211 a, a reflectedlight from the surface of the fixing belt 461 is generated. Since thesurface of the fixing belt 461 is not mirror surface, the reflectedlight includes a scattering light component is generated in addition tothe nominal reflecting light component. Therefore, the part of thereflected light is guided into the light-receiving lenses 22 a anddetected by the PD 212 a.

FIG. 26 is a schematic plan view of a board 210 a that supports an LED221 a and a PD 212 a in a view of z direction. The LED 211 a is arrangedwith a pitch Pa in the primary scanning direction in a unit and with apitch Pa′ in the primary scanning direction between the adjacent units.The PD 212 a is arranged with a pitch Pa″ in the primary scanning. Thepitch between the LED 211 a and the PD 212 a is Pa″″. Each of the LED211 a is named as LED 211 a-1, LED 211 a-2, . . . , LED 211 a-(N−1), LED211 a-N (since the quantity of units is seven, these names are actuallyLED 211 a-1 to LED211 a-28) from the left-hand side of FIG. 26 towardthe positive orientation in x direction and in the similar manner, eachof the PD 212 a as PD 211 a-1, PD 211 a-2, PD 211 a-(N′−1), LED 211 a-N′(named actually (LED 211 a-1 to LED 211 a-28).

(An Example for Comparison) (Structure of the Reflection Type OpticalSensors)

Using FIGS. 28A to 31, the reflection type optical sensors 200′ as givenas an example for comparison is concretely discussed. The structure ofthe reflection type optical sensors 200′ given as an example forcomparison has the same structure as the fourteenth embodiment withdifferences as described below. The same structure is not explained butthe differences from the fourteenth embodiment are only discussed in thefollowing.

The differences are;

-   (1) the reflection type optical sensors 200′ have light-blocking    members,-   (2) the light-emitting lenses 221′ and the light-receiving lenses    222′ are arranged in the same position in the optical axial    direction, and-   (3) the lens parameters (curvature radii, lens diameters, lens    thicknesses, light emitting systems), the center-to-center distance    to the light-emitting lenses and the center-to-center distance    between the light receiver system and light-receiving lenses.

FIG. 28A is a schematic of a conceptual cross-sectional view of areflection type optical sensor 200′ scanned in the primarily scanningdirection (x direction). FIG. 28B is a schematic of a conceptualcross-sectional view of the reflection type optical sensor 200′ scannedin the secondarily scanning direction).

FIG. 29 is a schematic cross-sectional view of a PD 212′ and thelight-receiving lenses 222′ included in the reflection type opticalsensor 200′ in the secondary scanning direction (y direction). FIG. 30is a schematic to explain a structure of the lens array 220′ included ina reflection type optical sensor 200′. FIG. 31 is a schematic of planview of the board that supports an LED 211′ and a PD 212′.

As shown in FIGS. 28A to 31, the reflection type optical sensors 200′regarding the example for comparison comprises an LED 221′ as the lightemitter systems, a light-emitting lens 221′ arranged to emit the lightto generate the optical spots SP on the surface of the fixing belt 462,a photodiode (a PD 212′) working as the light receiver system to receivethe reflected light being guided by the light-receiving lenses 222, alens array 220′ formed into a single element from the light-emittinglenses 221′ and the light-receiving lenses 222′, a case to hold theboard 210′ and the lens array 220′ and the light-blocking surroundingwall to prevent the flare.

The light-blocking surrounding walls 230′ that prevent to detect theflare is placed between the LED 211′ and the light-emitting lens 221′ inthe primary scanning direction. The light-blocking surrounding wall 230′and the case 240′ are formed into a single element.

FIG. 30 is a schematic to show the detail structure of the lens array220′ included in the reflection type optical sensor 200′. The lensparameters of the light-emitting lenses 221′ are 4.6 mm curvature radiusin the primary scanning direction and 0 conical constant in the primaryscanning direction. The curvature radius of the light-emitting lenses221 in the secondary scanning direction is 4.3 mm and the conicalconstant in the secondary scanning direction is −2.0. The lens diameterof the light-emitting lenses 221′ is 2.4 mm and 10.5 mm in the primaryand secondary scanning directions, respectively and the lens thicknessis 6.6 mm.

The curvature radius and the conical constant of the light-receivinglens 222′ in the primary scanning direction are 50 mm and −1.0,respectively. The curvature radius and the conical constant of thelight-receiving lenses 222′ in the secondary scanning direction is 4.8mm and −1.6, respectively. The lens thickness of the light-emitting lens221′ is 6.6 mm and the lens diameters of the light-emitting lens 221′are 2.4 mm and 10.5 mm in primary and secondary scanning directions,respectively.

The center-to-center distance (or the optical axis distance, i.e. thedistance between two optical axes) between the light-receiving lenses221′ in the secondary scanning direction and light-receiving lenses 222a is 2.53 mm. The center-to-center distance between the light emittersystems and the light-emitting lens 221′ in the optical axis which isequal to the center-to-center distance between the light receiver systemand light-receiving lens 222′ is 10.4 mm.

(First Example of the Operation of the Reflection Type Optical SensorsRegarding the Fourteenth Embodiment)

An example of the operation of the reflection type optical sensors isexplained specifically using the reflection type optical sensors 200 aregarding the fourteenth embodiment. FIG. 32 shows the operation flow,particularly process for each portion that constructs the reflectiontype optical sensors 200 a, for the case that the optical spots SP arescanned in the positive orientation in x direction shown in FIG. 26. Thesame operation in each portion is sustained for the example forcomparison and the following embodiments. In the fourteenth embodiment,sequential turning-on/off of the light such that each LED within unit issequentially turned-on and turned-off from the right to the left in FIG.26 with an order of unit 1, 2, . . . , 7, using an LED 211 a-1 to an LED211 a-28.

As shown in FIG. 32, the operation starts with setting L=1 (wherein L isin the range of 1<=L<=7) as an initial value for the unit number (stepS410). In the next step, a counter that controls the order of thesequential turning-on/off of the light is set as h=0 (wherein h is inthe range of 1<=h<=3) (step S411). In the step S412, an LED 211 a-n (nis a serial number of an LED 211 a and an integer in the range of1<=n<=28 and has the relation as n=4L−h) is turned on. For example,since in the first process where n=4, the LED 211 a-4 in the most rightin unit 1 turns on. In the next step, 2m pieces of a PD 212 a-(n−m) to aPD 212 a-(n+m) receive the reflected light that reflects on the surfaceof the fixing belt 461 (step S414). The details of receiving thereflected light are explained later.

Then an LED 211 a-n turns off (step S414) and each photodiode from thePD 212 a-(n−m) to the PD 212 a-(n+m) sends the detection signal to thesurface condition judging device 300 (step S415).

In the step S416, where h<3 is satisfied or not, that is, whether thesteps S412 to S415 have proceeded for all of the four pieces of the LED211 a or not is judged. If h<3 is satisfied, counting up of h (that ish=h+1) in step S417, the process comes back to the step S412. Then theprocesses in the steps S412 to S415 are recursively carried out. On theother hand, if n<N is not satisfied, the process goes to the step S418since the processes of all LEDs 211 a in the unit L have been completed.For example, it is judged that the processes of all of the LED 211 a inthe unit 1 are completed when the serial processes as turning-on of thelight, turning-off of the light and sending the detected signal havebeen completed.

In the step S418, whether L<7 is satisfied or not, that is, where allprocesses of steps S411 to S417 have been carried out or not is judged.If L<7 is satisfied, counting up L as h=h+1 (step S419), process goesback to the step S411. If L<7 is not satisfied, the process goes to thestep S420 since the processes for all units have been completed. In thepresent embodiment, when the process of the LED 211 a-25 which locatesin the left end in the seventh unit7 is completed, the first scanning(the total processes are called one cycle hereinafter) is ended. At thelast stage, whether the serial processes is repeated for another cycleis judged, if the judgment is “YES”, the process goes back to the stepS410 and repeats the steps from S411 to S419. If the judgment is “NO”,whole processes are ended.

The operation of the PD 212 a (such as step S413) in the time when theoptical spots SP are scanned in the positive orientation in the xdirection is explained as follows. Being synchronous to turning-on ofthe light of the n-th LED 211 a-n, the PDs 212 a receive the reflectedlight that reflected on the surface of the fixing belt 461. For thepurpose of the simplicity, the plurality of PDs 212 a is controlled toreceive the reflected light. In other words, 2m pieces of the PDs 212 areceive the reflected light.

The selection method of 2m pieces of the PDs 212 a is explained. Whenthe n-th LED 211 a-n turns on the light, two of the PDs 212 a such asone receives the maximum receiving light and the other the next maximumreceiving light are extracted. For the arrangement of the PDs 212 aregarding the fourteenth embodiment first, these two PDs 212 a areadjacent each other. The center of these two PDs 212 a in the xdirection being X0=0, the PD 212 arrange at x=0+/−1.51×P′″a is extractedfor the rest of 2m⁻² pieces of PDs 212 a. The variable X presents therelative distance from X0 in x direction, 1 an integer among 1, 2, . . ., m−1 and P′″a a pitch of an arrangement (see FIG. 26) in the primaryscanning direction regarding the fourteenth embodiment. In a samemanner, the distances of the arrangement gaps among a PD 212 b, a PD 212c, a PD 212 d in the primary scanning direction are set to be P′″b, P′″cand P′″d for the fifteenth to the seventeenth embodiments and P′″ forthe example for the comparison. The above constant 1.5 is to accept thedeviation of the center-to-center distance within the two adjacent PD212 a.

The reflected light that is received by 2m pieces of the PDs 212 a isphoto-electrically converted into a signal and amplified into adetection signal. The detection signal amplified by each PD 212 a issent to the surface condition judging device 300 for every time when thereflected light is detected. In order to raise the precision of thedetection, averaging process of the detection results is taken over aplurality of cycles. All of N pieces (N=28 for FIG. 26) of the LEDs 211a, from the left end to the right end as shown in FIG. 26, that turnson/off the light are not necessary to be used but an arbitral N′″ (where1<=N′″<=N is satisfied) pieces of the LEDs 211 a among N pieces can beusable. In the selection of N′″ pieces of the LEDs 211 a, every adjacentones or every two or three adjacent ones in accordance with theposition, size and the dimension to the primary scanning direction onthe fixing belt 461 may be selected. A combination of the LEDs 211 a inthe region where there is no scratch and a few of the LEDs 211 a in theregion where the scratches are actually made may be used. A single LED211 a locating in any one of the units is used.

(Operation of the Surface Condition Judging Device)

The operation of the surface condition judging device 300 is explainedusing the flow chart shown in FIG. 33. In the surface condition judgingdevice 300, 2m+1 pieces of PDs 212 a of the reflection type opticalsensors 200 a receive the light and send the detection signals (stepS520). Taking summation of the detection signals, the detection resultR−n corresponding to each LED 211 a-n is calculated. In other words,each optical spot SP forming in the primary scanning direction, thelight intensity of the reflected light can be obtained in correspondenceto each position on the fixing belt in the primary scanning direction.(step S521).

The judgment method of the surface condition of the fixing belt 461 isexplained. The nominal reflected light component decreases and thescattering light component increases in case that there are scratches onthe surface of the fixing belt 461 in comparison to the case that thereare no scratches on the surface of the fixing belt 461. In thereflection type optical sensors 200 a, as shown in FIGS. 23A and 23B,regarding the fourteenth embodiment and the reflection type opticalsensors 200′, as shown in FIG. 32, regarding an example for comparison,the received light received by the PD 212 a and the PD 212′ decreases asmuch as the decrease of the nominal reflected light component. Thereceived light received by the PD 212 a and the PD 212′ increases inaccordance with the increase of the scattering light component. As theresult, the intensity of the received light by the PD 212 a and the PD212′ decreases when there are scratches in comparison to when there areno scratches. According to the variation of the received light, thecondition of scratches, that is, the level of the scratches and theposition of the scratches are calculated.

The judgment of the positions of the scratches is explained. Since theintensity of the reflected light is determined in accordance to theposition on the surface of the fixing belt 461 in the primary scanningdirection, it is possible to understand that there are scratches in theposition on the surface where the intensity of the reflected light fromthe fixing belt 461 decreases in comparing the plurality of detectionsof the intensity of the reflected light in the primary scanningdirection. The perspective of the intensity of the reflected lightobtained by the reflection type optical sensors 200′ as shown in theexample for comparison is depicted in FIG. 34A. Taking the differentialof the intensity of the reflected light with regard to the primaryscanning direction (step S522), the positions of the scratches is judgedby obtaining a zero-cross position of the differential of the intensityof the reflected light with regard to the primary scanning direction(step S523). FIG. 34B shows the perspective of the differential of theintensity of the reflected light and the determination of the zero-crosspoint. It may be noted that it can be judged that there are no scratcheswhen the absolute values of the differential ones are less thanpre-determined value since the intensity of the reflected light isremarkably low against the surface that has no scratches.

In FIG. 35A, an example of the detection result R−n, using thereflection type optical sensor 200′, being given as an example forcomparison, that is specifically provided with N=24, n=3 to 22, m=2 andan arrangement pitch of LEDs 221′ P=1 mm for the fixing belt 461experienced with 400,000 pieces of recording papers passing, is shown.Since the light emitted to the surface of the fixing belt 461 with theoptical spots SP in P′=1 mm pitch for the reflection type optical sensor200′ given as the example for comparison, the abscissa axis of the FIG.35A corresponds to the light-illuminated positions (mm) of the opticalspots. As shown in FIG. 35B, the result of the differential with regardto the primary scanning direction is provided where the gradient of twopoints R−n and R−(n+1) is taken. For the purpose of smoothening, amoving average is taken over R−(n−1), R−n and R−(n+1).

According to FIG. 35B, determining n=12.5 as the zero-cross position, itis possible that there is a scratch in the middle point of thelight-illuminated position, which is 12.5 mm, of the optical spotscorresponding to the LED 122′-12 and the LED 211′-13 (these processesare shown in steps S522 to S524).

The judgment of the scratch level (the depths of the scratches) is done(the step S25) as shown in FIG. 34C. Since it is expected that thedeeper (rougher) the scratches are, the further the intensity of thereflected light decreases, it is possible to detect the depths of thescratches by measuring the decrease of the intensity of the reflectedlight. FIG. 34C is a schematic that depicts the perspective of suchdecrease of the intensity of the reflected light. For the case shown inFIG. 34C, the depths of the scratches are simply obtained by measuringthe minimum value for the detection result R−n, however it is expectedthat the light components due to the fixing status of the reflectiontype optical sensors 200′ in the image generation apparatus 1 and tiltof fixing belt 461 etc. is biased to the detection result R−n.Therefore, the decrease of the intensity of the reflected light can beobtained in the following processes.

The position of scratches is judged as n=12.5 in the steps from S522 toS523 and by FIG. 35B. The position where there is no scratches is theposition where the change of the detection result R−n is small, that isthe position where the differential values are close to zeros. In otherwords, it is possible to determine the position where there are noscratches by using the results of the differential value with regard tothe primary scanning direction. An example to determine decrease of theintensity of the reflected light is shown using the detection resultR−n0 at the position n0 where there are scratches and the detectionresults R−n1 and R−n2 at least two position n1 and n2 where there are noscratches.

In order to remove such component due to the gradient elementsuperimposed in the detection result R−n, the distance between thedetection result at the position where no scratches exist and theintensity of the reflected light at the position on an approximatedstraight line that goes through a plurality of detection results at thepositions where scratches do not exist is used. The determination of thedecrease of the intensity of the reflected light is actually explainedusing the results of FIGS. 35A and 35B. FIG. 36A shows the differentialvalues against the positions of the scratches calculated by the resultsshown in the FIG. 35B wherein rather small differential values within+/−20 are assembled in a certain of n. It is possible to select thepositions n−6 and 15 as those where there are no scratches (the stepS526).

Therefore, it is possible to calculate the depth (roughness) of scratchusing the each detection result R−n (step S527) after determiningn0=12.5 as the position where there are scratches and n1=6 and n2=15 asthe positions where there are no scratches. As shown in FIG. 36A, thebroken line is a straight line crossing Rn−n1 and Rn−n2 and an arrowsign with a broken line shows the depths of the scratches. For thisexample, the depth of the scratch is 63.1 mm (it is necessary to confirmthis unit). The decreasing rate of the intensity of the reflected lightis 0.16 (that is, 16%). It can be seen that the depth of the scratchesis superimposed to the gradient component shown in a broken line. Thelarger the level of the scratches becomes, the further the intensity ofthe reflected light decreases.

In order to judge the surface condition of the fixing belt 461, anotherparameter to judge the width (or the size) of scratches is explained(the step S528). The center position of the scratches is judged in thesteps from S522 to S523 and FIG. 35B. The positions at which theintensity of the reflected light that corresponds to the depth (orroughness) decrease to a predetermined intensity, for example, 50%thereof against the detection result R−n where there are scratches fromthe position thereof is calculate for the determination of the depths ofscratches. FIG. 37 has an enlarged the axis of ordinate of FIG. 36B. Itis possible to judge the half width of the scratch is 3 mm.

As explained above, all of the parameters such as depths of scratches(in the steps S525 to S527) and widths of scratches (the steps S528 andS529) may be assessed to be judged since it is possible to judge thedetails of the status of scratches by using all of these parameters. Thejudgment process can be quickly done by using only parameters that arenecessarily required.

(Comparison of the Effects Between the Fourteenth Embodiment and theExample for Comparison)

The results of variation regarding PD output (or output for thelight-receiving sensors) obtained in evaluation tests each using thereflection type optical sensors 200 of the fourteenth embodiment asshown in FIGS. 23 to 27 and the reflection type optical sensors 200′ arepresented in the diagrams shown in FIG. 38. Each diagram shows theresult of the PD output variation for each case of detecting such outputusing two, four, six, eight and ten pieces of the PD 212 a and the PD212′ with +/−50 micron meter deviation of lens array 220 a and 220′ insecondary scanning direction (Y named to be the deviation). Each diagramshows the results of PD output variation for several deviation ofelevation angle A which is applied to the fixing belt 461 as well. ThePD output is, as explained, the summation of the detection values of theplurality of PD 212 a and the PD 212′ are normalized as unity to the PDoutput wherein no deviation of the lens arrays 220 a and 220′ in thesecondary scanning direction and no deviation of the elevation angle A(that is, Y=0 and A=0). The normalized values are named as medianshereinafter. For the PD output, the flare being removed light, there isscarcely the difference of light intensity between the reflection typeoptical sensors 200′ regarding the example for comparison and thereflection type optical sensors 200 a regarding the fourteenthembodiment.

As clearly understood by FIG. 38, the reflection type optical sensors200 a regarding the fourteenth embodiment has less fluctuation of the PDoutput caused by the deviation of the elevation angle A in comparison tothe reflection type optical sensor 200′ regarding the example ofcomparison. The PD output deviates with +/−10% against the median if theelevation angle A is within +/−1.5 degrees even when the deviation inthe secondary scanning direction is +/−50 micron meter for the lensarray 220 a set to the light-receiving/emitting device.

As shown in FIG. 27, the light is reflected on the planner portion 223 a(as shown by an arrow with a two-dot chain line) which is set in thefourteenth embodiment. It is possible to reduce the light other thanthat necessary to detect the fixing belt 461 and suppress thedegradation of the detection precision of the reflection type opticalsensors 200 a.

As explained above, the reflection type optical sensors 200 a regardingthe fourteenth embodiment has good optical properties. The printer 100that uses the reflection type optical sensors 200 a precisely detectsthe surface conditions of the fixing belt 461 since the surfacecondition judging device 300 receive the detection signal from thereflection type optical sensors 200 a. The printer 100 can control toconvey the blanks not to be placed on the region which has largescratches on the fixing belt 461 or control to heavily put toner on theportion which has scratches on the fix belt 461 so that the scratchesare inconspicuous on the recording paper. Therefore the printer 100 caneffectively prevent the degradation of the image quality. By alarming ofbuzzers or displaying warnings, users can get to know the time toexchange the fixing belt 461. Therefore, it is possible to effectivelyuse the fixing belt 461 without exchanging the fixing belt 461 whichstill works well and does not damages to the image quality.

The Fifteenth Embodiment

The structure of the reflection type optical sensors 200 b regarding thefifteenth embodiment is explained using FIGS. 39A to 42. FIG. 39A is aschematic to explain a structure of the reflection type optical sensor200 b regarding the fifteenth embodiment, specifically a schematiccross-sectional view thereof along the direction of the primarilyscanning direction (x direction). FIG. 39B is a schematic to explain astructure of the reflection type optical sensor 200 b regarding thefifteenth embodiment, specifically a schematic cross-sectional viewthereof along the direction of the secondarily scanning direction (ydirection). FIG. 40 is a schematic cross-sectional view of the PD 212 band the light-receiving lens 222 b included in the reflection typeoptical sensor 200 b scanned along the direction of the secondaryscanning direction (y direction). FIG. 41 is a schematic to explaindetails of a light-emitting lens 221 b and a light-receiving lens 222 bincluded in a reflection type optical sensor. FIG. 42 is a schematicplan view of a board that supports the LED 221 b and the PD 212 b in zdirection.

As shown in FIGS. 39A to 42, the reflection type optical sensors 200 bregarding the fifteenth embodiment comprises a light-emitting opticalsystem including a light-emitting diode (LED) 211 b working as alight-emitting member (that is a light emitter system) andlight-emitting lenses 221 b arranged to emit the light to generate theoptical spots SP on the fixing belt 461, a light-receiving opticalsystem including light-receiving lenses 222 b arranged to guide thereflected light reflected at the fixing belt 461, a photo diode (PD) 212b working as a light-receiving member that receives the reflected lightguided by the light-receiving lenses 222 b, a board that supports an LED211 b and the PD 212 b and a case 240 b that holds a board 210 b and alens array 220 b. The reflection type optical sensors 200 b have aplanner portion (or a step) 223 b at the border between thelight-emitting lens 221 b and the light-receiving lens 222 b.

The structure of the reflection type optical sensors 220 b regarding thefifteenth embodiment is same as that of the reflection type opticalsensors 220 s regarding the fourteenth embodiment besides thelight-receiving lenses 222 b are arranged in the position that isfarther from the light receiver system than the arrangement adopted inthe fourteenth embodiment. The structure of the printer regarding thefifteenth embodiment is same as that of the printer 100 regarding thefourteenth embodiment besides the reflection type optical sensors 200 bare used instead of reflection type optical sensors 200 a. Therefore,detailed explanation will be omitted for the structure that is same asthat of the fourteenth embodiment and be provided for the structure thatis different from that of the fourteenth embodiment. The reflection typeoptical sensors 200 b are different from the reflection type opticalsensors 200 a in the following due to being placed at the position suchthat the light-receiving lenses 222 b are placed farther from the PD 212b than the structure adopted in the fourteenth embodiment.

The lens parameters (as curvature radius, lens diameter, lens thickness,center-to-center distance between the light emitter system and thelight-receiving lens and the center-to-center distance between the lightreceiver system and the light-receiving lens) are different from thoseof the fourteenth embodiment.

The light-emitting lens 221 b and the light-receiving lens 222 b have agap of 0.5 mm between their centers of the lens which is larger than thelenses regarding the fourteenth embodiment. The light-emitting lens 221b is placed closer to the light emitter system (or the LED 211 b) thanthe light-receiving lens 222 b is placed. As for the quantitativecharacteristics of the lens, in other words, the lens parameter is thatthe curvature radius and the conical constant of the light-emitting lens221 b in the primary scanning direction are 4.6 mm and 0, respectivelyand the curvature radius and the conical constant of the light-emittinglens 221 b in the secondary scanning direction are 4.3 mm and −2.0,respectively. The lens diameters of the light-emitting lens 221 b are2.4 mm and 9.2 mm, respectively. The lens thickness of thelight-emitting lens 221 b is 6.6 mm.

The curvature radius and the conical constant of the light-receivinglens 222 b in the primary scanning direction are 50 mm and −1.0,respectively. The curvature radius and the conical constant of thelight-receiving lens 222 b in the secondary scanning direction are 4.8mm and −1.6, respectively. The lens thicknesses of the light-receivinglens 222 b in the primary and secondary scanning directions are 17 mmand 5.6 mm, respectively.

The center-to-center distance between the light-emitting lens 221 b andlight-receiving lens 222 b (distance between two optical axes) is 2.53mm and the center-to-center distance between the light emitter system(or the LED 211 b) in the optical axis direction and the light-emittinglens 221 b is 10.37 mm and the center-to-center distance between thelight receiver system (or the PD 212 b) in the optical axis directionand light-receiving lens 222 b is 11.37 mm.

FIG. 43 shows a diagram of PD output using the reflection type opticalsensor 200 a regarding the fourteenth embodiment and the reflection typeoptical sensor 200 b regarding the fifteenth embodiment. Each diagramshows the result of the PD output variation for each case of detectingsuch output using two, four, six, eight and ten pieces of PDs 212 a andPDs 212 b with +/−50 micron meter deviation of lens array 220 a and 220b in secondary scanning direction (that is, Y=+/−50 micron meters). Eachdiagram shows the results of the PD output variation for severaldeviation of elevation angle A which is applied to the fixing belt 461as well. For the PD output, the flare being removed and there isscarcely the difference of light intensity in between the reflectiontype optical sensor 200 a regarding the fourteenth embodiment and thereflection type optical sensor 200 b regarding the fifteenth embodiment.

As clearly understood by FIG. 43, the reflection type optical sensors200 b regarding the fifteenth embodiment has less fluctuation of the PDoutput caused by the deviation of the elevation angle A in comparison tothe reflection type optical sensor 200 a regarding the fourteenthembodiment. The PD output deviates with +/−10% against the median if theelevation angle A is within +/−1.5 degrees even when the deviation inthe secondary scanning direction is +/−50 micron meter for the lensarray 220 b set to the light-receiving/emitting device.

As explained, it is possible to reduce the PD output variation causedthe deviation of elevation angle of the fixing belt 461 since thelight-receiving lens 222 b is placed farther from the PD 212 b incomparison to the fourteenth embodiment.

The Sixteenth Embodiment

The structure of the reflection type optical sensors 200 c regarding thesixteenth embodiment is explained using FIGS. 44A to 46. FIG. 44A is aschematic to explain the structure of the reflection type optical sensor200 c regarding the sixteenth embodiment, specifically a schematiccross-sectional view thereof along the direction of the primary scanningdirection (x direction). FIG. 44B is a schematic to explain a structureof the reflection type optical sensor 200 c regarding the sixteenthembodiment, specifically a schematic cross-sectional view thereof alongthe direction of the secondarily scanning direction (y direction). FIG.45 is a schematic cross-sectional view of a PD 212 c and thelight-receiving lens 222 c included in the reflection type opticalsensor 200 c scanned along the direction of the secondary scanningdirection (y direction). FIG. 42 is a schematic plan view of a boardthat supports an LED 221 c and the PD 212 c in z direction.

As shown in FIGS. 44A to 46, the reflection type optical sensors 200 cregarding the sixteenth embodiment comprises a light-emitting opticalsystem including a light-emitting diode (or LED) 211 c working as alight-emitting member (that is a light emitter system) andlight-emitting lenses 221 c arranged to emit the light to generate theoptical spots SP on the fixing belt 461, a light-receiving opticalsystem including light-receiving lenses 222 c arranged to guide thereflected light reflected at the fixing belt 461, a photo diode (or PD)212 c working as a light-receiving member that receives the reflectedlight guided by a light-receiving lenses 222 c, a board 210 c thatsupports the LED 211 c and the PD 212 c and a case 240 c that holds aboard 210 c and a lens array 220 c. The reflection type optical sensors200 c have a planner portion (or a step) 223 c at the border between thelight-emitting lens 221 b and the light-receiving lens 222 b.

The structure of the reflection type optical sensor 200 c regarding thesixteenth embodiment is same as that of the reflection type opticalsensor 200 a regarding the fourteenth embodiment other than that theformer sensor has a light-receiving lens 222 c instead of an anamorphiclens used in the latter sensor. The printer regarding the sixteenthembodiment has the same structure as the printer 100 regarding thefourteenth embodiment besides that the former printer uses thereflection type optical sensor 200 c. Therefore, detail explanation forthe structures which are same structures as the fourteenth embodiment isomitted in the following discussion.

The lens parameters regarding sixteenth embodiment are concretelyexplained. As for the light-emitting lenses 221 c, similar lenses tothose regarding the fourteenth and the fifteenth embodiments are usedand the lens parameters thereof are same. On the other hand, since thelight-receiving lens 222 c regarding the sixteenth is a cylindrical lensthat converts the light into a line, the curvature radius and theconical constant both in the primary scanning direction are onlydifferent from those regarding the fourteenth and the fifteenembodiments so that the curvature radius and the conical constant of thelight-receiving lens 222 c are infinity and zero both in the primaryscanning direction.

As shown in FIGS. 24 and 30, the reflection type optical sensors 200 aand 200 c regarding fourteenth and sixteenth embodiments are constructedsuch that the PD 212 a and the PD 212 c are arranged in the primaryscanning direction, respectively. Therefore, it is necessary that thelight incidental to a PD has to be converted in the secondary scanningdirection considering the position and size of the PD in relation to thesecondary scanning direction, however not in the primary scanningdirection by effecting of the light-receiving lenses therein.

Therefore, as explained above, cylindrical lens that has no opticalpower against the primary scanning direction is adopted to thelight-receiving lens 222 c regarding sixteenth embodiment. For suchstructure, it is possible to suppress the variation of the intensitydistribution of the receiving light by the PD against the difference ofthe LED 211 c that turns on the light, therefore to precisely detect thesurface condition of the fixing belt 461.

The Seventeenth Embodiment

The structure of a reflection type optical sensors 200 d regarding theseventeenth embodiment is explained using FIGS. 47A to 50. FIG. 47A is aschematic to explain a structure of the reflection type optical sensor200 d regarding the seventeenth embodiment, specifically a schematiccross-sectional view thereof along the direction of the primary scanningdirection (x direction). FIG. 47B is a schematic to explain a structureof the reflection type optical sensor 200 d regarding the sixteenthembodiment, specifically a schematic cross-sectional view thereof alongthe direction of the secondarily scanning direction (y direction). FIG.48 is a schematic cross-sectional view of a PD 212 d and alight-receiving lens 222 d included in the reflection type opticalsensor 200 d scanned along the direction of the secondary scanningdirection (y direction). FIG. 49 is a schematic to show the details of alight-emitting lens 221 d and a light-receiving lens 222 d regarding thereflection type optical sensor 200 d. FIG. 50 is a schematic plan viewof a board that supports the LED 221 c and the PD 212 c in z direction.

As shown in FIGS. 47A to 50, the reflection type optical sensors 200 dregarding the seventeenth embodiment comprises light-emitting diodes(LEDs) 211 d working as a light-emitting member (that is a light emittersystem), light-emitting lenses 221 d arranged to emit the light togenerate the optical spots SP on the fixing belt 461, light-receivinglenses 222 d arranged to guide the reflected light reflected at thefixing belt 461, photo diodes (PDs) 212 d working as a light-receivingmember that receives the reflected light guided by the light-receivinglenses 222 d, a board 210 d that supports the LED 211 b and the PD 212b, a lens array 220 d formed into a single element that includes thelight-emitting lens 221 d and the light-receiving lens 222 d, a case 240d that holds the board 210 d and the lens array 220 d, a light-blockingsurrounding wall 230 d, functioning to limit the incident light flux ofthe flare, that has an opening O therein. The reflection type opticalsensors 200 d have a planner portion (or a step) 223 d at the borderbetween the light-emitting lens 221 d and the light-receiving lens 222d.

The structure of the reflection type optical sensor 200 d regarding theseventeenth embodiment is same as that of the reflection type opticalsensor 200 c regarding the sixteenth embodiment other than that thelight-blocking surrounding wall 230 d functioning to limit the incidentlight flux of the flare wherein an opening O is formed. The printerregarding the seventeenth embodiment has the same structure as theprinter 100 regarding the fourteenth embodiment besides that the formerprinter uses the reflection type optical sensor 200 d. Therefore, detailexplanation for the structures which are same structures as thefourteenth embodiment is omitted in the following discussion.

Due to the light-blocking surrounding wall 230 d which surrounds thelight-emitting lens 221 d included in the reflection type optical sensor200 d regarding the seventeenth embodiment, it is possible to cut theflux of the light that passes the light-emitting lenses 221 d other thanthe light-emitting lens 221 d corresponding to an arbitral LED 211 dthat turns on the light or that of the flare that is the reflected lightdirectly reflected on the surface of the light-emitting lenses 221 dother than the light-emitting lens 221 d corresponding to the arbitralLED 211 d that turns on the light and the light-emitting lenses 221 dother than the light-emitting lens 221 d corresponding to the arbitralLED 211 d that turns on the light so that such flux of the light doesnot directly enter into the PD 222 d. As the results, it is possible toprecisely detect the surface condition of the fixing belt 461.

The case 240 d and the light-blocking surrounding wall 230 d includingthe opening O can be formed into a single element by plastic molding.

For forming the opening O which is the opening end of the light-blockingsurrounding wall 230 d, a planner portion (or a step) 223 d is used asthe reference surface. Using such reference, it is possible that thepositioning of the opening O as well as the light-blocking surroundingwall 230 d can be precisely done and the degradation of the performanceof the reflective sensor 200 d is suppressed. Forming the opening Oclose to the planner portion (or a step) 223 d, it is possible to removethe incidental light to the fixing belt 461 after passing through thelight-receiving lens 222 d and guide the incidental light that is guidedonto the fixing belt 461 after passing the light-emitting lens 221 d andthe light-receiving lens 222 d to be reflected at the planner portion(or a step) 223 d to the position which is apart, in the secondaryscanning direction, from the nominal position that the light reflectedon the fixing belt 461 arrives at after passing through thelight-receiving lens 222 d. Therefore, the reflection type opticalsensor 200 d can maintain extremely precise detection.

By using the reflection type optical sensors 200 b, 200 c, 200 dregarding the fifteenth to seventeenth embodiment, it is possible tosequentially turn-on/off the light. The functions of the reflection typeoptical sensors are not limited to theses ones explained above. Thesecond example of different operation is explained using the fourteen tothe seventeenth embodiment.

(The Second Example of the Reflection Type Optical Sensor)

The second examples of the reflection type optical sensors 200 (2001,200 b, 200 c, 200 d) regarding the fourteenth to the seventeenthembodiment are explained in the following paragraphs. It is possible toshorten the line cycle of optical scanning in the primary scanningdirection. FIGS. 51A and 51B show the result of the PD output obtainedin the second example.

For example, letting the quantity of the unit comprising four piece ofLEDs and one light-emitting lens be nine and unit 1, unit 2, . . . ,unit 9 are placed in x direction which is from the left to the right onFIG. 50. At the left end of unit 1 and the right end of unit 9, threepieces of PDs are additionally placed. Using such reflection type sensor200, a plurality of LEDs included in unit 2 to unit 8 is turning-on atthe time to detect the surface condition of the fixing belt 461. Fourpieces of LEDs are placed in the positive direction of x direction.These pieces of LEDs as named LED1, LED2, LED3 and LED4 are arranged inthis order. Therefore, LED3 in unit 2 is called LED2-3. As for PDs,those installed in nine units and additional 6 pieces that is 42 piecesin total are arranged in the order of PD_(—)1, PD_(—)2, PD_(—)42.

FIG. 51A shows the distribution of the PD output when LED2-3 turns onthe light. The maximum intensity of the PD output is normalized as unityand the PD outputs are zeros for PD_(—)1 to PD_(—)4 and PD_(—)15 toPD_(—)18. Therefore, ten pieces of PDs (as PD_(—)5 to PD_(—)14) are usedwhen LED2-3 (LED2-2) is turned on the light.

Two pieces, for example, of LEDs turn on the light, it is necessarythat, one an arbitral LED turns on the light, ten pieces of PDs that areused for the sensor detection do not receive the reflected lightgenerated by rest of one LED turning-on the light. Therefore, when aplurality of LEDs simultaneously turns on the light, those separatelyarranged in the primary scanning direction put may be used.

FIG. 52B shows the distribution of the PD output regarding a pluralityof PDs when light-emitting member LED2-3, LED5-3 and LED8-3 (the thirdLED in unit 2, unit 5 and unit 8). Even when these three pieces of LEDsturn on the light, the output of an arbitral PD that receive the lightthereof is equal to the output of an arbitral PD among a plurality ofPDs that receive the reflected light caused by a single LED turns on thelight.

For the example shown in FIG. 51B, it is possible to turn on the lightregarding LED1 included in unit 2, unit 5 and unit 8, LED2 included inunit 2, unit 5 and unit 8, LED4 included in unit 2, unit 5 and unit 8simultaneously turn on the light for each of unit2, unit 5 or unit 8. Itis also possible to turn on the light regarding LED 1 included in unit 3and unit 6, LED2 included in unit 3 and unit 6, LED4 included in unit 3and unit 6 simultaneously turn on the light for each of unit 3 or unit 6and LED 1 included in unit 4 and unit 7, LED2 included in unit 4 andunit 7, LED3 included in unit 4 and unit 7 simultaneously turn on thelight for each of unit 4 or unit 7.

Simultaneously turning on the light of a plurality of LEDs, it ispossible to shorten the line cycle of the optical scanning in primaryscanning direction. It is possible to improve the convey speed of thefixing belt 461 so that the time necessary for image generation can beshortened as well.

(Arrangement Angle of the Reflection Type Optical Sensor)

The reflection type optical sensors 200 (as 200 a, 200 b, 200 c and 200d) regarding to the fourteenth to seventeenth embodiments, are arrangedin parallel to the primary scanning direction of the fixing belt 461.The present invention is not limited to such structure but can beprovided in such arrangement that these reflection type optical sensors200 are arranged in the direction different to the primary scanningdirection. It is possible to make the pitch of the optical spot SP inthe primary scanning direction small. FIG. 52A shows thelight-illuminated positions of the optical spots SP for the case whenthe reflection type optical sensors are arranged in the primary scanningdirection.

FIG. 52B shows the reflection type optical sensor is placed in such thatthe longitudinal axis thereof has 45 degrees angle against the primaryscanning direction. In such arrangement, the detection region A′ of theprimary scanning direction and the pitch of the optical spot SP reducesby 1/square root of 2. Therefore, it is possible to improve thepositional resolution of the detection results using the reflection typeoptical sensor by detecting narrow detection region A′ with the samequantity of the optical spots SP, in comparison to the arrangement shownin FIG. 52A. The angle is not limited within 45 degrees, it may beappropriately selected in accordance with the widths etc. of thescratches. In the present embodiment, the reflection type optical sensor200 is arranged with a declined angle to the primary scanning direction,but the arrangement is not limited with such declined angle. FIG. 52Bshows another arrangement of the reflection type optical sensorregarding the present embodiment as the reflection type optical sensor200 may be arranged in parallel to the primary scanning direction andthe optical spots generated by the emitting light from the LED 211 has arow declined to the primary scanning direction. For such arrangement,the same effect such as improving the positional resolution.

As explained above, the inventions regarding the fourteenth toseventeenth embodiments that has the reflection type optical sensors 200a, 200 b, 200 c and 200 d in the image generation apparatus (that is theprinter 100) enables to detect the scratches in a real-time fashion andalso detect the positions and widths of the scratches on the fixingbelt, which has not been possible. Modifying the light-receiving sensors200 a, 200 b, 200 c and 200 d and the optical system for thelight-emitting member and sensors light-emitting member, it is possibleto increase the intensity of the reflected light from the fixing belt461 and improve the precision of detecting the scratches on the surfaceof the fixing belt 461.

For the reflection type optical sensors 200 a, 200 b, 200 c and 200 dregarding the fourteenth and the seventeenth embodiment, the preferablearrangement of the fixing belt 461 is explained. These reflection typeoptical sensors 200 a, 200 b, 200 c and 200 d are, as shown in FIGS. 53Ato 53C, preferably placed near the passing region Edg through which theperiphery portion in the width direction of the small size blankspasses. As shown in FIG. 53A, a passing region Edg that the peripheryedge of width direction of the blanks passes through is included in thedetection region A even when the width in the primary scanning in thedetection region A is narrowed. Since the detection region A can beshortened, these embodiments imply the merit that the reflection typeoptical sensors 200 can be specifically shortened in the primaryscanning direction. The widths of scratches are several hundred micronmeters to several millimeters and positions of the scratches deviatewithin several millimeters at the center position. Therefore thedetection region A is preferable set in 5 mm to 15 mm in the primaryscanning direction.

For the image generation apparatus of the present invention, a pluralityof various sizes of blanks such as A3, A4 and A5 sizes can be used. Formany kinds of the image generation apparatus, the maximum size of theblanks is A3 in the longitudinal-laid direction. Therefore, the smallsize blanks imply the blanks excluding the A3 size one. If the imagegeneration apparatus can print the A2 size blanks in longitudinal-laiddirection, then the small size blanks implies those excluding A2 size.

There are two passing regions Edg where the periphery edge of small sizeblanks in the width direction pass through on the fixing belt 461,however as shown in FIGS. 53A, 53B and 53C, the reflection type opticalsensors 200-1 and those 200-2 may be placed each at the both peripheryends of the blanks, so that two in total, in the primary scanningdirection. By using such setting of the reflection type optical sensors,it is possible to surely detect the scratches. However, the presentinvention is not limited to such setting, it may be acceptable to seteach of the reflection type optical sensors in only one side either ofboth sides of the blanks since the longitudinal streak scratches causedby the end surfaces of the blanks are generated on both periphery sidesof the blanks and there are no remarkable differences between thosescratches one in the one side and the others in the other side thereof.The use of a single reflection type optical sensor can reduce thefacility cost.

The reflection type optical sensors 200 (including 200 a, 200 b, 200 c,200 d) regarding each of the embodiments may be formed large in theprimary scanning direction as shown in FIG. 54 so that the sizes thereofin such direction are substantively same as the width of the fixing belt461 and the image generation apparatus or the present inventionresultantly supports the printing various size of blanks. For example,the image generation apparatus of the present invention adopts thereflection type optical sensors 200 that is formed largely in theprimary scanning direction in order to the passing region Edg of theperiphery edges of blanks in the width direction can be emitted by thereflection type optical sensor 200 then the image generation apparatusof the present invention can detect the surface condition of the fixingbelt 461 as well as support the printing of the various size of theblanks. In the operation of the reflection type optical sensor 200, allLEDs can be turned on or part thereof can be turned on in response tothe sizes of the blanks. In order to allow the change of the sizes ofthe blanks, for example, the LEDs that are near to the region throughwhich the edges of the blanks pass are only used based on theinformation detected by the printer body regarding the blanks that areconveyed on the fixing belt. For this design of the printer body, it ispossible to save energy by confining the necessary LEDs to turn on thelight so that it is possible to precisely the surface condition of thefixing belt such as the scratches on the fixing belt as well as energyefficiency can be improved.

In the selection of the fixing members (moving bodies), any of thetechnologies or materials in the public domain may be adopted howeverthe fixing belts which have no peripheries are preferable to be used.The surface of the fixing belt is easily scratched since the surface iscoated with a material such as PFA etc. Inner stress, seam, orinhomogeneity of the surface condition in the secondary scanningdirection of the fixing belt causes the difference of the reflectionangle against the flat surface of the fixing belt at the different placethereof to detect. However, the image generation apparatus having thereflection type optical sensors regarding the present invention canprecisely detect the surface condition even if the image generationapparatus uses such fixing belt that the detection characteristics ofsurface condition in the secondary direction vary on the position of thefixing belt.

The image generation apparatus having the reflection type opticalsensors regarding fourteenth to seventeenth embodiments have beenexplained however these are the parts of the embodiments that implementthe present invention. The present invention is not limited in theseembodiments. The reflection type optical sensors that can emit the lightto form the plurality of optical spots in the primary scanning directionon the surface of the fixing belt can solve the problems that have beenunsolved before the present invention is made.

The reflection type optical sensors regarding each embodiment include aplurality of LEDs and PDs of which each LED and each PD are set opposingin a fashion of one-to-one correspondence. A single LED of which emittedlight is deflected and form the optical spots on the fixing belt whereinthe reflected light from such the optical spots are detected by a singleor a plurality of PDs can be preferably used for the present invention.The structure that the reflection type optical sensors having an LED anda PD is driven by a drive device in the primary scanning direction ofthe fixing belt. Further preferably used for the present invention.

According to the above discussion, the present invention has thefollowing effects.

It is possible to precisely detect the surface condition at eachposition in the with direction of the moving body by comparing thereceived light received by at least row light-receiving members, whereinthe received light is reflected on the surface of the moving body eachemitted from at least two light-emitting members. For example, it ispossible to detect existence of actual scratches on the moving body andthe precise status of the scratches such as the positions, depths andwidths of the scratches.

According to the present invention, it is possible to provide thereflection type optical sensors having such good optical characteristicsto robustly detect the surface condition of moving bodies such as fixingbelts without the influences of ghost light generated in the lightemission to and/or the light reception from the moving bodies. By usingthe reflection type optical sensors regarding the present invention, itis possible to so precisely detect the variation of the surfacecondition of the moving bodies that the image generation apparatushaving such reflection type optical sensors enables to realize and keephigh quality of the images and further to cut the cost for maintenanceetc. of the image generation apparatus by reducing the frequency ofexchanging fixing members that are consumables of such image generationapparatus.

As some preferred embodiments in the present invention have beendisclosed and explained their details in the above discussion. However,the present invention is not limited to these embodiments. One skilledin the art should understand that various modifications and changes canbe made in these embodiments.

Since many embodiments of the invention can be made without departingfrom the spirit and scope of the invention, the invention also residesin the claims hereinafter appended.

What is claimed is:
 1. A reflection type optical sensor detecting asurface condition of a moving body and being used for an imagegeneration apparatus which forms images on a recording media,comprising: a light-emitting device which has a plurality of lightemitter systems including at least two light-emitting members and alight-emitting optical system having a plurality of light-emittinglenses corresponding to a plurality of the light emitter systems andguiding light emitted from the light emitter systems to the moving body;and a light-receiving device which has a light receiver system includingat least two light-receiving members and a light-receiving opticalsystem having light-receiving lenses corresponding to the at least twolight-receiving members and guiding light reflected by the moving bodyto the light receiver system.
 2. The reflection type optical sensor ofclaim 1, wherein the light emitter systems are arranged in a directionsuch that optical axes of a plurality of light-emitting lensescorresponding to each of the light emitter systems are between arbitraltwo of the at least two light-receiving members or near thereby.
 3. Thereflection type optical sensor of claim 1, wherein the light-emittinglenses and the light-receiving lenses corresponding to the at least twolight-receiving members are formed into a single element and centers ofthe light-receiving lenses locate in different positions with respect toan optical axis of the light-emitting lens and a planner portionparallel to the optical axis is formed therein at a border between thelight-emitting lenses and the light-receiving lenses.
 4. The reflectiontype optical sensor of claim 2, wherein the at least light-emittingmembers of the light emitter system are arranged to have surfacesymmetry to a surface which includes an optical axis of thelight-emitting lens corresponding thereto.
 5. The reflection typeoptical sensor of claim 2, wherein the light-receiving lens is placed ata position in the optical axis of the light-receiving lens farther thana position of the light-emitting lens from the light-emitting member inthe optical axis of the light emitter system.
 6. The reflection typeoptical sensor of claim 1, wherein an open-end space is formed betweenthe light-emitting system and the light-emitting optical system.
 7. Thereflection type optical sensor of claim 1, wherein the light-receivinglens is a cylindrical lens which converts an incidental light only intothe direction of an arrangement of the light-receiving members.
 8. Thereflection type optical sensor of claim 1, wherein the light-emittinglens comprising the light-emitting optical system and thelight-receiving lens comprising the light-receiving optical system areformed into a single element.
 9. The reflection type optical sensor ofclaim 1, wherein a light-blocking member is made between the lightemitter system and the light-emitting optical system.
 10. The reflectiontype optical sensor of claim 1, wherein the optical spots generated onthe moving body by light emitted from the at least light-emittingmembers sequentially turn on/off by turning-on/off the light therefrom.11. The reflection type optical sensor of claim 1, wherein the opticalspots are simultaneously generated by the at least light-emittingmembers.
 12. The reflection type optical sensor of claim 1, wherein aline formed by the optical spots has an arbitral declination angel tothe direction of an arrangement of a plurality of the light emittersystems.
 13. The image generation apparatus of claim 1, wherein thereflection type optical sensor detects the surface condition of themoving body which fixes images on the recording media.
 14. The imagegeneration apparatus of claim 1, wherein the reflection type opticalsensor is placed at a width periphery position of the recording mediawhich the moving body conveys or near thereby or over a whole width ofthe recording media.
 15. The image generation apparatus of claim 1,wherein the moving body is a fixing belt.